**Go Math Grade 1 Chapter 8 Answer Key Pdf:** Elementary School Kids will feel the math concepts enjoyable to learn and teach by referring to our Go Math Grade 1 Answer Key Chapter 8 Two-Digit Addition and Subtraction. HMH Go Math Grade 1 Answers are thoughtfully constructed with an intense focus on key concepts of the Grade 1 Curriculum. Deepen your knowledge and enhance your math proficiency by learning the problem-solving approach from First Grade Go Math Chapter 8 Two-Digit Addition and Subtraction Answer Key.

## Two-Digit Addition and Subtraction Go Math Grade 1 Chapter 8 Answer Key Pdf

With consistent practice from the HMH Go Math 1st Grade Ch 8 Solutions you can gain a complete body of math knowledge other than a discrete set of skills. Topicwise Go Math Grade 1 Chapter 8 Answer Key will create enduring knowledge that will stay with you from grade to grade. Look no further! and begin your preparation taking the help of the quick links available below. Simply click on the quick links to avail the respective topics within them easily.

**Two-Digit Addition and Subtraction**

- Two-Digit Addition and Subtraction Show What You Know – Page 434
- Two-Digit Addition and Subtraction Vocabulary Builder – Page 435
- Two-Digit Addition and Subtraction Game Neighborhood Sums – Page 436

**Lesson: 1 Add and Subtract Within 20**

- Lesson 8.1 Add and Subtract Within 20 – Page(437-442)
- Add and Subtract Within 20 Homework & Practice 8.1 – Page(441-442)

**Lesson: 2 Add Tens**

**Lesson: 3 Subtract Tens**

**Mid-Chapter Checkpoint**

**Lesson: 4 Use a Hundred Chart to Add**

- Lesson 8.4 Use a Hundred Chart to Add – Page(455-460)
- Use a Hundred Chart to Add Homework & Practice 8.4 – Page(459-460)

**Lesson: 5 Use Models to Add**

- Lesson 8.5 Use Models to Add – Page(461-466)
- Use Models to Add Homework & Practice 8.5 – Page(465-466)

**Lesson: 6 Make Ten to Add**

**Lesson: 7 Use Place Value to Add**

- Lesson 8.7 Use Place Value to Add – Page(473-478)
- Use Place Value to Add Homework & Practice 8.7 – Page(477-478)

**Lesson: 8 Problem Solving • Addition Word Problems**

- Lesson 8.8 Problem Solving • Addition Word Problems – Page(479-484)
- Problem Solving • Addition Word Problems Homework & Practice 8.8 – Page(483-484)

**Lesson: 9 Related Addition and Subtraction**

- Lesson 8.9 Related Addition and Subtraction – Page(485-490)
- Related Addition and Subtraction Homework & Practice 8.9 – Page(489-490)

**Lesson: 10 Practice Addition and Subtraction**

- Lesson 8.10 Practice Addition and Subtraction – Page(491-496)
- Practice Addition and Subtraction Homework & Practice 8.10 – Page(495-496)
- Two-Digit Addition and Subtraction Review/Test – Page(497-500)

### Two-Digit Addition and Subtraction Show What You Know

Add and Subtract

Use and to add. Write the sum.

Break apart to subtract.

Write the difference.

Question 1.

Answer:

Explanation:

Given 4 red cubes and 1 blue cubes

In the first expression 4 red cubes + 1 blue cubes gives the sum 5.

In the second expression sum 5 – 1 blue cube gives the difference 4.

Count Groups to 20

Circle groups of 10. Write how many.

Question 2.

Answer:

Explanation:

Their are total 14 stars. 7 in first row and another 7 in second row.

To get the total of 10 we need to circle 7 in row and 3 in the second row.

Question 3.

Answer:

Answer:

5 stars + 5 stars = 10 stars.

Explanation:

Given total 12 stars

5 in first row , 2 in second row, 5 in third row.

Adding 5 and 5 gives the sum 10.

5 + 5 = 10.

Use a Hundred Chart to Count

Touch and count. Shade the last number counted.

Question 4.

Start at 1 and count to 20.

Answer:

Explanation:

start from 1.

From 1 count on ten ones to 10 and from 10 count on one tens to 20. We get the required answer 1 to 20.

Question 5.

Start at 30 and count to 56.

Answer:

Start at 30 count on two tens to 50. From 51 count on six ones to reach 56.

Explanation:

To reach from 30 to 56

we need to count on two tens from 30 to 40, 40 to 50 and six ones from 51 to 52, 52 to 53, 53 to 54, 54 to 55, 55 to 56.

Question 6.

Start at 77 and count to 93.

Answer:

Explanation:

Start from 77 count on 3 ones to 80.

77 to 78, 78 to 79, 79 to 80

Start from 80 count on 1 tens to 90.

80 to 90

From 91 count on 3 ones to 93.

91 to 92, 92 to 93.

### Two-Digit Addition and Subtraction Vocabulary Builder

Visualize It

Sort the review words from the box.

Answer:

**Understand Vocabulary**

Use a review word to complete each sentence.

Question 1.

8 is the _____ for 17 _____ 9.

Answer:

8 is the **difference** for 17 **subtract** 9.

Question 2.

17 is the _____ for 8 + 9.

Answer:

17 is the **sum** for 8 + 9.

Question 3.

When you _____ 4 to 8, you find the sum.

Answer:

When you **add** 4 to 8, you find the sum.

Question 4.

When you _____ 4 from 8, you find the difference.

Answer:

When you **subtract** 4 from 8, you find the difference.

### Two-Digit Addition and Subtraction Game Neighborhood Sums

Materials

Play with a partner.

- Put your on START.
- Spin the . Move that number of spaces.
- Make a ten to help you find the sum.
- The other player uses to check.
- If you are not correct, you lose a turn.
- The first player to get to END wins.

Two-Digit Addition and Subtraction Vocabulary Game

Materials

1 set of word cards

- 18 https://gomathanswerkeys.com/wp-content/uploads/2021/02/1st-Grade-Go-Math-Answer-Key-Chapter-8-Two-Digit-Addition-and-Subtraction-2.4.png” alt=”1st Grade Go Math Answer Key Chapter 8 Two-Digit Addition and Subtraction 2.4″ width=”40″ height=”36″ class=”alignnone size-full wp-image-12779″ />

How to Play

Play with a partner.

- Mix the cards. Put the cards in a pile with the blank side up.
- Take a card. Read the word.
- Find the matching word on your Bingo board. Cover the word with a . Put the card at the bottom of the pile.
- The other player takes a turn.
- The first player to cover 3 spaces in a line wins. The line may go across or down.

**The Write Way**

Reflect

Choose one idea. Draw and write about it.

- Write sentences that include at least two of these terms.

add subtract addition sentence subtraction sentence - Explain how you would solve this problem.

53 + 20 = _____

### Lesson 8.1 Add and Subtract Within 20

**Essential Question** What strategies can you use to add and subtract?

**Listen and Draw**

What is 5 + 4? Use a strategy to solve the addition fact. Draw to show your work.

5 + 4 = _____

Answer:

5 + 4 = 9

5 + 4 is a addition sentence where 5 and 4 add to give the sum 9.

**MATHEMATICAL PRACTICES**

Apply What strategy did you use to find the answer?

Answer:

Related fact.

**Share and Show**

Add or subtract.

Question 1.

5 + 3 = _____

Answer:

5 + 3 = 8.

Explanation:

Given addition expression adding 5 and 3 gives the sum 8.

Question 2.

10 – 5 = _____

Answer:

10 – 5 = 5.

Explanation:

Given a subtraction expression subtracting 5 from 10 gives the difference 5.

5 + 5 = 10 adding the difference and the subtrahend gives the minuend.

Question 3.

3 + 6 = ____

Answer:

3 + 6 = 9

Explanation:

Given addition expression adding 3 and 6 gives the sum 9.

Question 4.

12 – 5 = ____

Answer:

12 – 5 = 7.

Explanation:

Given a subtraction expression subtracting 5 from 12 gives the difference 7.

7 + 5 = 12 adding the difference and the subtrahend gives the minuend.

Question 5.

15 – 9 = ____

Answer:

15 – 9 = 6.

Explanation:

Given a subtraction expression subtracting 9 from 15 gives the difference 6.

9 + 6 = 15 adding the difference and the subtrahend gives the minuend.

Question 6.

5 + 7 = ____

Answer:

5 + 7 = 12

Explanation:

Given addition expression adding 5 and 7 gives the sum 12.

Question 7.

8 + 7 = ____

Answer:

8 + 7 = 15.

Explanation:

Given addition expression adding 8 and 7 gives the sum 15.

Question 8.

9 – 7 = ____

Answer:

9 – 7 = 2

Explanation:

Given a subtraction expression subtracting 7 from 9 gives the difference 2.

2 + 7 = 9 adding the difference and the subtrahend gives the minuend.

Question 9.

5 + 5 = ___

Answer:

5 + 5 = 10

Explanation:

Given addition expression adding 5 and 5 gives the sum 10.

Question 10.

12 – 7 = ____

Answer:

12 – 7 = 5

Explanation:

Given a subtraction expression subtracting 7 from 12 gives the difference 5.

5 + 7 = 12 adding the difference and the subtrahend gives the minuend.

Question 11.

18 – 9 = ____

Answer:

18 – 9 = 9

Explanation:

Given a subtraction expression subtracting 9 from 18 gives the difference 9.

9 + 9 = 18 adding the difference and the subtrahend gives the minuend.

Question 12.

9 + 4 = ____

Answer:

9 + 4 = 13

Explanation:

Given addition expression adding 9 and 4 gives the sum 13.

Question 13.

2 + 7 = ___

Answer:

2 + 7 = 9

Explanation:

Given addition expression adding 2 and 7 gives the sum 9.

Question 14.

5 – 1 = ____

Answer:

5 – 1 = 4.

Explanation:

Given a subtraction expression subtracting 1 from 5 gives the difference 4.

1 + 4 = 5 adding the difference and the subtrahend gives the minuend.

Question 15.

9 + 1 = ____

Answer:

9 + 1 = 10

Explanation:

Given addition expression adding 9 and 1 gives the sum 10.

Question 16.

7 – 6 = ____

Answer:

7 – 6 = 1

Explanation:

Given a subtraction expression subtracting 6 from 7 gives the difference 1.

1 + 6 = 7 adding the difference and the subtrahend gives the minuend.

Question 17.

13 – 4 = ____

Answer:

13 – 4 = 9

Explanation:

Given a subtraction expression subtracting 4 from 13 gives the difference 9.

9 + 4 = 13 adding the difference and the subtrahend gives the minuend.

Question 18.

2 + 6 = ____

Answer:

2 + 6 = 8

Explanation:

Given addition expression adding 2 and 6 gives the sum 8.

**On Your Own**

**MATHEMATICAL PRACTICE** Apply Add or subtract.

Question 19.

Answer:

14 – 5 = 9

Explanation:

Given a subtraction expression subtracting 5 from 14 gives the difference 9.

9 + 5 = 14 adding the difference and the subtrahend gives the minuend.

Question 20.

Answer:

2 + 10 = 12

Explanation:

Given addition expression adding 2 and 10 gives the sum 12.

Question 21.

Answer:

3 + 3 = 6

Explanation:

Given addition expression adding 3 and 3 gives the sum 6.

Question 22.

Answer:

14 – 8 = 6

Explanation:

Given a subtraction expression subtracting 8 from 14 gives the difference 6.

6 + 8 = 14 adding the difference and the subtrahend gives the minuend.

Question 23.

Answer:

8 + 9 = 17

Explanation:

Given addition expression adding 8 and 9 gives the sum 17.

Question 24.

Answer:

6 – 3 = 3

Explanation:

Given a subtraction expression subtracting 3 from 6 gives the difference 3.

3 + 3 = 6 adding the difference and the subtrahend gives the minuend.

Question 25.

Answer:

6 – 5 = 1

Explanation:

Given a subtraction expression subtracting 5 from 6 gives the difference 1.

1 + 5 = 6 adding the difference and the subtrahend gives the minuend.

Question 26.

Answer:

2 + 8 = 10

Explanation:

Given addition expression adding 2 and 8 gives the sum 10.

Question 27.

Answer:

0 + 5 = 5

Explanation:

Given addition expression adding 0 and 5 gives the sum 5.

Adding any number to zero gives the sum the number itself.

Question 28.

Answer:

10 – 2 = 8

Explanation:

Given a subtraction expression subtracting 2 from 10 gives the difference 8.

8 + 2 = 10 adding the difference and the subtrahend gives the minuend.

Question 29.

Answer:

9 + 9 = 18

Explanation:

Given addition expression adding 9 and 9 gives the sum 18.

Question 30.

Answer:

5 – 4 = 1

Explanation:

Given a subtraction expression subtracting 4 from 5 gives the difference 1.

1 + 4 = 5 adding the difference and the subtrahend gives the minuend.

Question 31.

Answer:

8 – 8 = 0

Explanation:

Given a subtraction expression subtracting 8 from 8 gives the difference 0.

0 + 8 = 8 adding the difference and the subtrahend gives the minuend.

Question 32.

Answer:

10 + 1 = 11

Explanation:

Given addition expression adding 10 and 1 gives the sum 11.

Question 33.

Answer:

4 + 7 = 11

Explanation:

Given addition expression adding 4 and 7 gives the sum 11.

Question 34.

Answer:

9 – 3 = 6

Explanation:

Given a subtraction expression subtracting 3 from 9 gives the difference 6.

6 + 3 = 9 adding the difference and the subtrahend gives the minuend.

Question 35.

Answer:

1 + 8 = 9.

Explanation:

Given addition expression adding 1 and 8 gives the sum 9.

Question 36.

Answer:

17 – 9 = 8

Explanation:

Given a subtraction expression subtracting 9 from 17 gives the difference 8.

8 + 9 = 17 adding the difference and the subtrahend gives the minuend.

Question 37.

Answer:

13 – 7 = 6.

Explanation:

Given a subtraction expression subtracting 7 from 13 gives the difference 6.

6 + 7 = 13 adding the difference and the subtrahend gives the minuend.

Question 38.

Answer:

6 + 5 = 11

Explanation:

Given addition expression adding 6 and 5 gives the sum 11.

Question 39.

Answer:

10 + 2 = 12.

Explanation:

Given addition expression adding 2 and 10 gives the sum 12.

Question 40.

Answer:

14 – 9 = 5.

Explanation:

Given a subtraction expression subtracting 9 from 14 gives the difference 5.

5 + 9 = 14 adding the difference and the subtrahend gives the minuend.

Question 41.

Answer:

10 + 10 = 20

Explanation:

Given addition expression adding 10 and 10 gives the sum 20.

Question 42.

Answer:

11 – 3 = 8

Explanation:

Given a subtraction expression subtracting 3 from 11 gives the difference 8.

8 + 3 = 11 adding the difference and the subtrahend gives the minuend.

Question 43.

**THINK SMARTER**

Jamal thinks of an addition fact. The sum is 15. One addend is 8. What is a fact Jamal could be thinking of?

Answer:

Given

Sum = 15

1st addend is = 8

2nd addend = sum – 1st addend

15- 8 = 7.

7 is the 2nd addend.

7 + 8 = 15.

**Problem Solving • Applications**

Solve. Write or draw to explain.

Question 44.

**THINK SMARTER**

There are 9 ants on a rock. Some more ants get on the rock. Now there are 18 ants on the rock. How many more ants got on the rock?

______ more ants

Answer:

Given:

Number of ants on the rock at first = 9 ants

Total number of after adding some more ants on the rock = 18 ants

Number of ants that got on the rock = total – number of ants at first

18 – 9 = 9 ants.

9 more ants got added to the rock.

9 ants + 9 ants = 18 ants.

Question 45.

**GO DEEPER**

Fill in the blanks. Write a number sentence to solve. Lin sees _____ bees. Some bees flew away. Now there are _____ bees. How many bees flew away?

______ bees

Answer:

Assume:

Total number of bees Lin sees= 10 bees.

Number of bees after some flew away = 5 bees

Number of bees flew away = total bees – number of bees after some flew away

10 – 5 = 5 bees.

Question 46.

**THINK SMARTER**

Write each addition or subtraction in the box below the answer

Answer:

**TAKE HOME ACTIVITY** • Have your child tell a strategy he or she would use to solve 4 + 8.

### Add and Subtract Within 20 Homework & Practice 8.1

Add or subtract.

Question 1.

Answer:

6 + 0 = 6

Explanation:

Given addition expression adding 10 and 10 gives the sum 20.

Question 2.

Answer:

11 – 2 = 9

Explanation:

Given a subtraction expression subtracting 2 from 11 gives the difference 9.

9 + 2 = 11 adding the difference and the subtrahend gives the minuend.

Question 3.

Answer:

4 + 5 = 9

Explanation:

Given addition expression adding 4 and 5 gives the sum 9.

Question 4.

Answer:

9 + 8 = 17

Explanation:

Given addition expression adding 9 and 8 gives the sum 17.

Question 5.

Answer:

4 + 10 = 14

Explanation:

Given addition expression adding 4 and 10 gives the sum 14.

Question 6.

Answer:

14 – 9 = 5

Explanation:

Given a subtraction expression subtracting 9 from 14 gives the difference 5.

5 + 9 = 14 adding the difference and the subtrahend gives the minuend.

Question 7.

Answer:

7 + 4 = 13

Explanation:

Given addition expression adding 7 and 4 gives the sum 13.

Question 8.

Answer:

8 – 5 = 3

Explanation:

Given a subtraction expression subtracting 5 from 8 gives the difference 3.

5 + 3 = 8 adding the difference and the subtrahend gives the minuend.

Question 9.

Answer:

10 – 1 0 = 0

Explanation:

Given a subtraction expression subtracting 10 from 10 gives the difference 0.

10 + 0 = 10 adding the difference and the subtrahend gives the minuend.

Question 10.

Answer:

6 + 7 = 13

Explanation:

Given addition expression adding 6 and 7 gives the sum 13.

Question 11.

Answer:

18 – 9 = 9

Explanation:

Given a subtraction expression subtracting 9 from 18 gives the difference 9.

9 + 9 = 18 adding the difference and the subtrahend gives the minuend.

Question 12.

Answer:

15 – 6 = 9

Explanation:

Given a subtraction expression subtracting 6 from 15 gives the difference 9.

9 + 6 = 15 adding the difference and the subtrahend gives the minuend.

**Problem Solving**

Solve. Draw or write to explain.

Question 13.

Jesse has 4 shells. He finds some more. Now he has 12 shells. How many more shells did Jesse find?

_______ more shells

Answer:

Number of shells Jesse had at first = 4 shells

After finding some more

Total number of shells Jesse have =12 shells

Number of shells Jesse find= Total shells – number of shells at first

12 – 4 = 8

Jesse found 8 more shells.

Question 14.

**WRITE**

Write an addition and subtraction fact. Then write a strategy you could use to solve the fact.

__________________

___________________

Answer:

8 + 9 = 17

9 – 8 = 1

The strategy i used to solve it is related fact.

**Lesson Check**

Question 1.

What is the sum? Write the number.

8 + 5 = ______

Answer:

8 + 5 = 13

13 is the SUM.

Explanation:

Sum is the result of adding two or more numbers.

8 and 5 are two number which are added to get the sum 13.

Question 2.

What is the difference? Write the number.

11 – 4 = ______

Answer:

11 – 4 = 7

7 is the difference between 11 and 4.

Explanation:

Difference is the result of subtracting one number from another.

4 is subtracted from 11 and got the difference 7.

**Spiral Review**

Question 3.

Answer:

Explanation:

46 is greater than 43.

Both the numbers are in the same tens place of four. But the ones place are different first one is at 3 and the other is at 6 . Since 6 is greater then 3. 46 is greater than 43.

Question 4.

Answer:

Explanation:

Given two number

69 – its at 6 tens and 9 ones

84- its at 8 tens and 4 ones

as per the above 69 is less then 84 as it is 2 tens less than 84.

### Lesson 8.2 Add Tens

**Essential Question** How can you add tens?

**Listen and Draw**

Choose a way to show the problem. Draw a quick picture to show your work.

**MATHEMATICAL PRACTICES**

Reasoning Why will there be no ones in your answer when you add 20 + 30?

Answer:

There are no ones when we add 20 and 30 because they both are in tens places and there is no ones place in both the number.

20 + 30 = 50

**Model and Draw**

How can you find 30 + 40?

Answer:

**Share and Show**

Use . Draw to show tens. Write the sum. Write how many tens.

Question 1.

20 + 40 = ______

_____ tens

Answer:

Explanation:

ONE line represents tens

1 line = 10

20 + 40 = 60

60 = 6 lines

Question 2.

30 + 30 = ______

______ tens

Answer:

30 + 30 = 60

Each line represents 1 Tens.

Explanation:

ONE line represents tens

1 line = 10

30 + 30 = 60

60 = 6 lines

Question 3.

40 + 50 = ______

_____ tens

Answer:

40 + 50 = 90

Each line represents Tens.

Explanation:

ONE line represents tens

1 line = 10

40 + 50 = 90

90 = 9 lines

Question 4.

50 + 30 = _____

_____ tens

Answer:

50 + 30 = 80

Each line represents Tens.

Explanation:

ONE line represents tens

1 line = 10

50 + 30 = 80

80 = 8 lines

**On Your Own**

**MATHEMATICAL PRACTICE** Represent a Problem Draw to show tens. Write the sum. Write how many tens.

Question 5.

40 + 40 = _____

____ tens

Answer:

40 + 40 = 80

Explanation:

ONE line represents tens

1 line = 10

40 + 40 = 80

80 = 8 lines

Question 6.

70 + 20 = _____

______ tens

Answer:

70 + 20 = 90

Explanation:

ONE line represents tens

1 line = 10

70 + 20 = 90

90 = 9 lines

Question 7.

10 + 80 = _____

_____ tens

Answer:

10 + 80 = 90

Explanation:

ONE line represents tens

1 line = 10

10 + 80 = 90

90 = 9 lines

Question 8.

60 + 80 = _____

_____ tens

Answer:

60 + 80 = 140

Explanation:

ONE line represents tens

1 line = 10

60 + 80 = 140

140 = 14 lines

Question 9.

**GO DEEPER**

Draw two groups of tens you can add to get a sum of 50. Write the number sentence.

Answer:

We can represent a group of tens that add together to a sum of 50 in different ways as below.

20 + 30 = 50

10 + 40 = 50

These two number sentences gives the sum 50 on adding two groups of tens.

**Problem Solving • Applications**

Question 10.

**THINK SMARTER**

Complete the web. Write the missing addend to get a sum of 90.

Answer:

Question 11.

**THINK SMARTER**

Choose all the ways that name the model.

Answer:

7 Tens

70

**TAKE HOME ACTIVITY** • Ask your child to explain how to use tens to find 20 + 70.

### Add Tens Homework & Practice 8.2

Draw to show tens. Write the sum. Write how many tens.

Question 1.

10 + 30 = ____

_____ tens

Answer:

10 + 30 = 40

Explanation:

ONE line represents tens

1 line = 10

10 + 30 = 40

40 = 4 lines

Question 2.

30 + 30 = _____

____ tens

Answer:

30 + 30 = 60

Explanation:

ONE line represents tens

1 line = 10

30 + 30 = 60

60 = 6 lines

Question 3.

60 + 10 = _____

_____ tens

Answer:

60 + 10 = 70

Explanation:

ONE line represents tens

1 line = 10

60 + 10 = 70

70 = 7 lines

Question 4.

10 + 70 = _____

_____ tens

Answer:

10 + 70 = 80

Explanation:

ONE line represents tens

1 line = 10

70 + 10 = 80

80 = 8 lines

**Problem Solving**

Draw tens to solve.

Question 5.

Drew makes 20 posters. Tia makes 30 posters. How many posters do they make?

______ posters

Answer:

Number of posters Drew made = 20

Number of posters Tia made = 30

Total number of posters both Drew and Tia make = Number of posters made by Drew + Number of posters made by Tia

20 + 30 = 50

Total 50 posters made by both.

Question 6.

Regina read 40 pages. Alice read 50 pages. How many pages did they read?

______ pages

Answer:

Number of pages Regina read = 40

Number of pages read by Alice = 50

Total number of pages read by both = Number of pages read by Regina + Number of pages read by Alice

40 + 50 = 90

Total 90 pages read by both.

Question 7.

**WRITE**

Choose an addition problem from the spider web on page 446. Draw a quick picture and write the number sentence.

Answer:

I choose 70 + 20 = 90

Explanation:

ONE line represents tens

1 line = 10

70 + 20 = 90

90 = 9 lines

**Lesson Check**

Question 1.

What is the sum? Write the number.

20 + 30 = _____

Answer:

20 + 30 = 50

Explanation:

ONE line represents tens

1 line = 10

20 + 30 = 50

50 = 5 lines

Question 2.

What is the sum? Write the number.

30 + 10 = _____

Answer:

30 + 10 = 40

Explanation:

ONE line represents tens

1 line = 10

30 + 10 = 40

40 = 4 lines

**Spiral Review**

Question 3.

Write a doubles fact that can help you solve 6 + 5 = 11

___ + ___ = _____

Answer:

6 + 5 = 11

(3 +3) + (3 + 3 ) = 11

6 + 6 =11

12 =11

The above expression is doubles minus 1

Question 4.

Circle the number sentences that are true. Cross out the number sentences that are false. Which is not true?

30>10

30<10

10>30

10<30

Answer:

### Lesson 8.3 Subtract Tens

**Essential Question** How can you subtract tens?

**Listen and Draw**

Choose a way to show the problem. Draw a quick picture to show your work.

**MATHEMATICAL PRACTICES**

Represent How does your picture show the first problem?

Answer:

**Model and Draw**

How can you find 80 – 30

Answer:

**Share and Show**

Use . Draw to show tens. Write the difference. Write how many tens.

Question 1.

60 – 20 = ____

_____ tens

Answer:

60 – 20 = 40

Explanation:

We subtract the subtrahend from the minuend to get the difference.

60 – 20 = 40

60 is minuend and 20 is subtrahend and 40 is difference of both

ONE line represents tens

1 line = 10

60 – 20 = 40

40 = 4 lines

Question 2.

70 – 30 = ____

_____ tens

Answer:

70 – 30 = 40

Explanation:

We subtract the subtrahend from the minuend to get the difference.

70 – 30 = 40

70 is minuend and 300 is subtrahend and 40 is difference of both

ONE line represents tens

1 line = 10

70 – 30 = 40

40 = 4 lines

Question 3.

80 – 20 = ____

____ tens

Answer:

80 – 20 = 60

Explanation:

We subtract the subtrahend from the minuend to get the difference.

80 – 20 = 60

80 is minuend and 20 is subtrahend and 60 is difference of both

ONE line represents tens

1 line = 10

80 – 20 = 60

60 = 6 lines

Question 4.

90 – 40 = ____

____ tens

Answer:

90 – 40 = 50

Explanation:

We subtract the subtrahend from the minuend to get the difference.

90 – 40 = 50

90 is minuend and 40 is subtrahend and 50 is difference of both

ONE line represents tens

1 line = 10

90 – 40 = 50

50 = 5 lines

**On Your Own**

**MATHEMATICAL PRACTICE** Make Connections Draw to show tens. Write the difference. Write how many tens.

Question 5.

80 – 40 = ____

____ tens

Answer:

Explanation:

We subtract the subtrahend from the minuend to get the difference.

80 – 40 = 40

80 is minuend and 40 is subtrahend and 40 is difference of both

ONE line represents tens

1 line = 10

80 – 40 = 40

40 = 4 lines

Question 6.

90 – 70 = ____

____ tens

Answer:

Explanation:

We subtract the subtrahend from the minuend to get the difference.

90 – 70 = 20

90 is minuend and 70 is subtrahend and 20 is difference of both

ONE line represents tens

1 line = 10

90 – 70 = 20

20 = 2 lines

Question 7.

70 – 50 = ____

____ tens

Answer:

Explanation:

We subtract the subtrahend from the minuend to get the difference.

70 – 50 = 20

70 is minuend and 50 is subtrahend and 20 is difference of both

ONE line represents tens

1 line = 10

70 – 50 = 20

20 = 2 lines

Question 8.

30 – 30 = ____

____ tens

Answer:

Explanation:

We subtract the subtrahend from the minuend to get the difference.

30 – 30 = 0

30 is minuend and 30 is subtrahend and 0 is difference of both

ONE line represents tens

1 line = 10

30 – 30 = 0

0 = 0 lines

**THINK SMARTER** Solve.

Question 9.

Jeff has 40 pennies. He gives some to Jill. He has 10 pennies left. How many pennies does Jeff give to Jill?

______ pennies

Answer:

Number of pennies Jeff has = 40 pennies

After giving some to Jill

Number of pennies left with Jeff = 10 pennies

Number of pennies Jeff gave to Jill = number of pennies Jeff had – Number of pennies left after giving to Jill

40 – 10 = 30 pennies.

**TAKE HOME ACTIVITY** • Ask your child to explain how to use tens to find 90 − 70.

### Subtract Tens Homework & Practice 8.3

Draw to show tens. Write the difference. Write how many tens.

Question 1.

40 – 10 = ______

____ tens

Answer:

40 – 10 = 30

Explanation:

We subtract the subtrahend from the minuend to get the difference.

40 – 10 = 30

40 is minuend and 10 is subtrahend and 30 is difference of both

ONE line represents tens

1 line = 10

40 – 10 = 30

30 = 3 lines

Question 2.

80 – 40 = ____

____ tens

Answer:

Explanation:

We subtract the subtrahend from the minuend to get the difference.

80 – 40 = 40

80 is minuend and 40 is subtrahend and 40 is difference of both

ONE line represents tens

1 line = 10

80 – 40 = 0

40 = 4 lines

**Problem Solving**

Draw tens to solve.

Question 3.

Mario has 70 baseball cards. He gives 30 to Lisa. How many baseball cards does Mario have left?

______ baseball cards

Answer:

Total number of baseball cards Mario has = 70

Number of cards he gave to Lisa = 30

Number of baseball cards left with Mario = Total cards – Number of cards he gave to Lisa

70 – 30 = 40 left.

Question 4.

**WRITE**

Draw a picture to show how to solve 50 – 40.

Answer:

50 – 40 = 10

Explanation:

We subtract the subtrahend from the minuend to get the difference.

50 – 40 = 10

30 is minuend and 30 is subtrahend and 0 is difference of both

ONE line represents tens

1 line = 10

50 – 40 = 10

10 = 1 lines

**Lesson Check**

Question 1.

What is the difference? Write the number.

60 – 20 = ____

Answer:

60 -20 = 40

Explanation:

We subtract the subtrahend from the minuend to get the difference.

60 – 20 = 40

60 is minuend and 20 is subtrahend and 40 is difference of both

ONE line represents tens

1 line = 10

60 – 20 = 40

40 = 4 lines

Question 2.

What is the difference? Write the number.

70 – 30 = ____

Answer:

70 – 30 = 40

Explanation:

We subtract the subtrahend from the minuend to get the difference.

70 – 30 = 40

70 is minuend and 30 is subtrahend and 40 is difference of both

ONE line represents tens

1 line = 10

70 – 30 = 40

40 = 4 lines

**Spiral Review**

Question 3.

Use ◯, , and a ten frame. Show both addends. Draw to make ten. Then write a new fact. Add.

Answer:

Question 4.

Bo crosses out the number cards that are less than 33 and greater than 38. What numbers are left?

Number cards _____ and _____ are left.

Answer:

36 , 37 are the number cards that are left.

### Two-Digit Addition and Subtraction Mid-Chapter Checkpoint

**Concepts and Skills**

Add or subtract.

Question 1.

Answer:

4 + 8 = 12

Explanation:

Given addition sentence 4 and 8 are addends. when we add both the addend we get the sum

4 + 8 = 12

12 is the sum

Question 2.

Answer:

15 – 7 = 8

Explanation:

Given Subtraction sentence. We subtract the subtrahend from the minuend to get the difference.

15 – 7 = 8

15 is minuend and 7 is subtrahend and 8 is difference

Question 3.

Answer:

9 – 6 = 3

Explanation:

Given Subtraction sentence. We subtract the subtrahend from the minuend to get the difference.

9 – 6 = 3

9 is minuend and 6 is subtrahend and 3 is difference.

Question 4.

Answer:

3 + 1 = 4

Explanation:

Given addition sentence 3 and 1 are addends. when we add both the addend we get the sum

3 + 1 = 4

4 is the sum

Question 5.

Answer:

10 + 6 = 16

Explanation:

Given addition sentence 10 and 6 are addends. when we add both the addend we get the sum

10 + 6 = 16

16 is the sum

Question 6.

Answer:

11 – 2 = 9

Explanation:

Given Subtraction sentence. We subtract the subtrahend from the minuend to get the difference.

11 – 2 = 9

11 is minuend and 2 is subtrahend and 9 is difference .

Use . Draw to show tens. Write the sum. Write how many tens.

Question 7.

30 + 50 = _____

_____ tens

Answer:

30 + 50 = 80

Explanation:

ONE line represents tens

1 line = 10

30 + 50 = 80

80 = 8 lines

Question 8.

40 + 20 = _____

______ tens

Answer:

40 +20 = 60

Explanation:

ONE line represents tens

1 line = 10

40 + 20 = 60

60 = 6 lines

Use . Draw to show tens. Write the difference. Write how many tens.

Question 9.

90 – 20 = _____

_____ tens

Answer:

90 – 20 = 70

Explanation:

We subtract the subtrahend from the minuend to get the difference.

90 – 20 = 70

90 is minuend and 20 is subtrahend and 70 is difference of both

ONE line represents tens

1 line = 10

90 – 20 = 70

70 = 7 lines

Question 10.

60 – 40 = _____

____ tens

Answer:

60 – 40 = 20

Explanation:

We subtract the subtrahend from the minuend to get the difference.

60 – 40 = 20

60 is minuend and 40 is subtrahend and 20 is difference of both

ONE line represents tens

1 line = 10

60 – 40 = 20

20 = 2 lines

Question 11.

**THINK SMARTER**

Mike has 60 marbles. He gives 20 to Kathy. How many marbles does Mike have left? Show your work.

_______ marbles

Answer:

Total number of marbles with Mike = 60

Number of marbles Mike gave to Kathy = 20

Number of marbles left with Mike = Total marbles – number of marbles he gave to Kathy

60 – 20 = 40

### Lesson 8.4 Use a Hundred Chart to Add

**Essential Question** How can you use a hundred chart to count on by ones or tens?

**Listen and Draw**

Use the hundred chart to solve the problems.

**MATHEMATICAL PRACTICES**

Explain how you can use a hundred chart to find each sum.

Answer:

**Share and Show**

Use the hundred chart to add. Count on by ones or tens.

Question 1.

42 + 7 = _____

Answer:

42 + 7 = 49

Explanation:

From 42 we need to count 7 to reach 49.

To reach 49 we need to count 7 ones from 42.

Question 2.

57 + 30 = _____

Answer:

57 + 30 = 87

Explanation:

To count 30 from 57

we need to count 3 ones from 57 to 60

2 tens count from 60 to 80

From 81 need to count 7 ones to 87.

10 ones count and 2 tens count.

Question 3.

91 + 5 = _____

Answer:

91 + 5 = 96

Explanation:

91 + 5 = 96

There is a 5 ones count from 91 to 96.

Question 4.

18 + 50 = _____

Answer:

18 + 50 = 68

Explanation:

From 18 we need to count 50

18 + 50 = 68

To reach 68 from 18

we need 10 ones count and 4 tens count.

18 to 20 – 2 ones counts and 61 to 68 – 8 ones counts.

20 to 60 we need 4 tens count.

**On Your Own**

**MATHEMATICAL PRACTICE** Use Appropriate Tools Use the hundred chart to add. Count on by ones or tens.

Question 5.

13 + 70 = ____

Answer:

13 + 70 = 83

Explanation:

From 13 we need to count 70

13 + 70 = 83

To reach 83 from 13

we need 10 ones count and 6 tens count.

13 to 20 – 7 ones counts and 20 to 80 – 6 tens counts.

80 to 83 we need 3 ones count.

Question 6.

22 + 6 = ____

Answer:

22 + 6 = 28

Explanation:

From 22 we need to count 6

22 + 6 = 28

To reach 28 from 22

we need 6 ones count.

Question 7.

71 + 3 = ____

Answer:

71 + 3 = 74

Explanation:

From 71 we need to count 3

71 + 3 = 74

To reach 74 from 71

we need 3 ones count.

71 – 74 we need 3 ones count.

Question 8.

49 + 50 = ____

Answer:

49 + 50 = 99

Explanation:

From 49 we need to count 50

49 + 50 = 99

To reach 99 from 49

we need 10 ones count and 4 tens count.

49 to 50 – 1 ones counts and 50 to 90 – 4 Tens counts.

90 – 99 we need 9 ones count.

Question 9.

53 + 4 = ____

Answer:

53 + 4 = 57

Explanation:

From 53 we need to count 4

53 + 4 = 57

To reach 57 from 53

we need 4 ones count.

53 – 57 we need 4 ones count.

Question 10.

25 + 40 = ____

Answer:

25 + 40 = 65

Explanation:

From 25 we need to count 40

25 + 40 = 65

To reach 65 from 25

we need 10 ones count and 3 tens count.

25 to 30 – 5 ones counts and 30 to 60 – 3 tens counts.

60 to 65 we need 5 ones count.

Question 11.

**GO DEEPER**

Solve. Show your work.

31 + 20 + 40 = ____

Answer:

31 + 20 + 40 = 91

Explanation:

From 31 we need to count 20 first

31 + 20 = 51

To reach 51 from 31

we need 10 ones count and 1 tens count.

31 to 40 – 9 ones counts and 40- 50 1 tens counts.

50 – 51 we need 1 ones count.

From 51 we need to count 40 more

51 + 40 = 91

To reach 91 from 51

we need 10 ones count and 3 tens count.

51 to 60 – 9 ones counts and 60- 90 3 tens counts.

90 – 91 we need 1 ones count.

**Problem Solving • Applications**

Choose a way to solve. Draw or write to show your work.

Question 12.

**THINK SMARTER**

Rae put 20 books away. She put 20 more books away, then 11 more. How many books did Rae put away?

______ books

Answer:

Number of books Rae puts away at first = 20

Number of books Rae puts away at second =20

Number of books Rae puts away at Last = 11

Total number of books Rae puts away = 20 + 20 + 11 = 51 books

Explanation:

From 1 we need to count 20 first

0 + 20 = 20

To reach 20 from 1

we need 10 ones count and 1 tens count.

1 to 10 – 9 ones counts and 10- 20 1 tens counts.

From 20 another 20 count is added

From 20 we need to count 20 more

20 + 20 = 40

To reach 40 from 20

we need 10 ones count and 1 tens count.

20 to 30 – 10 ones counts and 30- 40 1 tens counts.

From 40 count another 11

40 +11 = 51

To reach 51 from 40 we need 11 one counts .

Question 13.

**THINK SMARTER+**

Use the hundred chart to add. Count on by ones or tens.

62 + 9 = _____

Explain how you used the chart to find the sum.

Answer:

62 + 9 = 71

**TAKE HOME ACTIVITY** • On a piece of paper, write 36 + 40. Ask your child to explain how to use the hundred chart to count on by tens to find the sum.

### Use a Hundred Chart to Add Homework & Practice 8.4

Use the hundred chart to add. Count on by ones or tens.

Question 1.

47 + 2 = ____

Answer:

Explanation:

from 47 count 2

47 + 2 = 49

to reach 49 from 47 count 2 ones.

Question 2.

26 + 50 = ____

Answer:

26+50=76

Explanation:

From 26 we need to count 50

26 + 50 = 76

To reach 76 from 26

we need 10 ones count and 4 tens count.

26 to 30 – 4 ones counts and 30 to 70 – 4 tens counts.

70 to 76 we need 6 ones count.

Question 3.

22 + 5 = ____

Answer:

22 + 5 = 27

Question 4.

4 + 85 = ____

Answer:

**Problem Solving**

Choose a way to solve. Draw or write to show your work.

Question 5.

17 children are on the bus. Then 20 more children get on the bus. How many children are on the bus now?

______ children

Answer:

Number of students in the bus at first = 17

Later few more got into the bus

Number of students who got into the bus later = 20

Total number of students in the bus =

17 + 20 = 37

Total 37 students in the bus.

Question 6.

**WRITE**

Write a number sentence to add 6 ones to 21. Write a number sentence to add 6 tens to 21.

Answer:

Number sentence to add 6 ones to 21

21 + 6 =27

Number sentence to add 6 tens to 21

21 + 60 = 81

**Lesson Check**

Question 1.

What is the sum? Write the number.

42 + 50 = _____

Answer:

42 + 50 = 92

Question 2.

What is the sum? Write the number.

11 + 8 = _____

Answer:

11 + 8 = 19

**Spiral Review**

Question 3.

Use mental math. What number is ten less than 52? Write the number.

______

Answer:

Number Ten less than 52 = 52 – 10 = 42

42 is the number.

Question 4.

Write an addition fact that helps you solve 16 − 9.

____ + ____ = _____

Answer:

16 – 9 = 7

7 + 9 = 16.

### Lesson 8.5 Use Models to Add

**Essential Question** How can models help you add ones or tens to a two-digit number?

**Listen and Draw**

Draw to show how you can find the sum.

14 + 5 = _____

Answer:

Explanation:

14 = 1 tens and 4 once

5 = 5 ones

when adding 14 + 5 = 19

we add the ones and keep the tens constant as their is no tens place in the second addend

1 tens + (4 + 5)ones = 1 tens + 9 ones

19

**MATHEMATICAL PRACTICES**

Model Explain how you found the sum.

Answer:

**Share and Show**

Use . Draw to show how to add the ones. Write the sum.

Question 1.

27 + 2 = _____

Answer:

Explanation:

27 = 2 tens and 4 ones

2 = 2 ones

when adding 27 + 2

we add the ones and keep the tens constant as their is no tens place in the second addend

2 tens + (7 + 2)ones = 2 tens + 9 ones

27 + 2 = 29

Question 2.

41 + 5 = ____

Answer:

Explanation:

41 = 4 tens and 1 ones

5 = 5 ones

when adding 41 + 5

we add the ones and keep the tens constant as their is no tens place in the second addend

4 tens + (1 + 5)ones = 4 tens + 6 ones

41 + 5 = 46

Use . Draw to show how to add the tens. Write the sum.

Question 3.

13 + 50 = _____

Answer:

Explanation:

13 = 1 tens and 3 ones

50 = 5 tens

when adding 13 + 50

we add the tens and keep the ones constant as their is no ones place in the second addend

(1 tens + 3 ones) + 5 tens = (1 + 5) tens + 3 ones

6 tens + 3 ones

13 + 50 = 63.

Question 4.

28 + 30 = _____

Answer:

Explanation:

28 = 2 tens and 8 ones

30 = 3 tens

when adding 28 + 30

we add the tens and keep the ones constant as their is no ones place in the second addend

(2 tens + 8 ones) + 3 tens = (2 + 3) tens + 8 ones

5 tens + 8 ones

28 + 30 = 58.

**On Your Own**

**MATHEMATICAL PRACTICE** Use Models

Use and your MathBoard. Add the ones or tens. Write the sum.

Question 5.

65 + 3 = ____

Answer:

Explanation:

65 = 6 tens and 5 ones

3 = 3 ones

when adding 65 + 3

we add the ones and keep the tens constant as their is no tens place in the second addend

(6 tens +5 ones) + 3 ones = 6 tens +(5 + 3) ones

6 tens + 8 ones

65 + 3 = 68.

Question 6.

81 + 8 = _____

Answer:

Explanation:

81 = 8 tens and 1 ones

8 = 8 ones

when adding 81 + 8

we add the ones and keep the tens constant as their is no tens place in the second addend

(8 tens + 1 ones) + 8 ones = 8 tens +(8+1)ones

8 tens + 9 ones

81 + 8 = 89

Question 7.

54 + 20 = ____

Answer:

Explanation:

54 = 5 tens and 4 ones

20 = 2 tens

when adding 54 + 20

we add the tens and keep the ones constant as their is no ones place in the second addend

(5 tens + 4 ones) + 2 tens = (5 + 2) tens + 4 ones

7 tens + 4 ones

54 + 20 = 74

Question 8.

32 + 10 = ____

Answer:

Explanation:

32 = 3 tens and 2 ones

10 = 1 tens

when adding 32 + 10

we add the tens and keep the ones constant as their is no ones place in the second addend

(3 tens + 2 ones) + 1 tens = (3 + 1) tens + 2 ones

4 tens + 2 ones

32 + 10 = 42.

Question 9.

95 + 2 = ____

Answer:

Explanation:

95 = 9 tens and 5 ones

2 = 2 ones

when adding 95 + 2

we add the ones and keep the tens constant as their is no tens place in the second addend

(9 tens + 5 ones) + 2 ones = 9 tens +(5+2)ones

9 tens + 7 ones

95 + 2 = 97

Question 10.

25 + 60 = ____

Answer:

Explanation:

25 = 2 tens and 5 ones

60 = 6 tens

when adding 25 + 60

we add the tens and keep the ones constant as their is no ones place in the second addend

(2 tens + 5 ones) + 6 tens = (2 + 6) tens + 5 ones

8 tens + 5 ones

25 + 60 = 85.

Question 11.

2 + 54 = _____

Answer:

Explanation:

54 = 5 tens and 4 ones

2 = 2 ones

when adding 2 + 54

we add the ones and keep the tens constant as their is no tens place in the first addend

2 ones + 5 tens + 4 ones = 5 tens +(2+4)ones

5 tens + 6 ones

2 +54 = 56

Question 12.

70 + 29 = ____

Answer:

Explanation:

29 = 2 tens and 9 ones

70 = 7 tens

when adding 70 + 29

we add the tens and keep the ones constant as their is no ones place in the second addend

7 tens + 2 tens 9 ones = (7+ 2) tens + 9 ones

9 tens + 9 ones

70 + 29 = 99

**GO DEEPER** Make a sum of 45. Draw a quick picture. Write the number sentence.

Question 13.

Add ones to a two-digit number.

_____ + _____ = 45

Answer:

5 + 40 = 45

Question 14.

Add tens to a two-digit number.

_____ + _____ = 45

Answer:

20 + 25 = 45

**Problem Solving • Applications**

Choose a way to solve. Draw or write to show your work.

Question 15.

Rita picks 63 strawberries. Then she picks 30 more. How many strawberries does Rita pick?

_____ strawberries

Answer:

Number of strawberries Rita picked at first = 63

Number of more strawberries Rita picked = 30

Total number of strawberries Rita picked = 63 + 30 = 93.

Question 16.

**THINK SMARTER**

Kenny planted two rows of corn. He used 20 seeds in each row. He has 18 seeds left. How many seeds of corn did Kenny have?

_____ seeds

Answer:

Number of seeds in a row = 20

Number of rows = 2

Total number of seeds planted in 2 rows = 2 × 20 = 40

Number of seed left = 18

Total number of seeds = 40 + 18 = 58

Question 17.

There are 7 oak trees and 32 pine trees in the park. How many trees are in the park?

_____ trees

Number of oak trees = 7

Number of pine trees = 32

Total number of trees in park =7 + 32 = 39

Answer:

Question 18.

**THINK SMARTER**

Use the model. Draw to show how to add the tens.

Answer:

**TAKE HOME ACTIVITY** • Give your child the addition problems 25 + 3 and 25 + 30. Ask your child to explain how to solve each problem.

### Use Models to Add Homework & Practice 8.5

Use and your MathBoard. Add the ones or tens. Write the sum.

Question 1.

44 + 5 = _____

Answer:

Explanation:

44 = 4 tens and 4 ones

5 = 5 ones

when adding 44 + 5

we add the ones and keep the tens constant as their is no tens place in the first addend

4 tens + 4 ones +5 ones = 4 tens +(4+5)ones

4 tens + 9 ones = 49

44 + 5 = 49

Question 2.

16 + 70 = _____

Answer:

Question 3.

78 + 20 = _____

Answer:

Question 4.

52 + 7 = _____

Answer:

Explanation:

52 = 5 tens and 2 ones

7 = 7 ones

when adding 52 + 7

we add the ones and keep the tens constant as their is no tens place in the first addend

5 tens + 2 ones +7 ones = 5 tens +(2+7)ones

5 tens + 9 ones = 59

52+ 7 = 59.

Question 5.

2 + 13 = _____

Answer:

Explanation:

2 = 2 ones

13 = 1 tens and 3 ones

when adding 2 +13

we add the ones and keep the tens constant as their is no tens place in the first addend

2 ones + 1 tens + 3 ones + = 1 tens +(2+3)ones

1 tens + 5 ones = 15

2 + 13 = 15

Question 6.

73 + 4 = ____

Answer:

Explanation:

73 = 7 tens and 3 ones

4 = 4 ones

when adding 73 + 4

we add the ones and keep the tens constant as their is no tens place in the first addend

7 tens + 3 ones + 4 ones = 7 tens +(3+4)ones

7 tens + 7 ones = 77

73 + 4 = 77

Question 7.

65 + 3 = ____

Answer:

Explanation:

65 = 6 tens and 5 ones

3 = 3 ones

when adding 65 + 3

we add the ones and keep the tens constant as their is no tens place in the first addend

6 tens + 5 ones +3 ones = 6 tens +(5+3)ones

6 tens + 8 ones = 68

65 +3 =68..

Question 8.

20 + 25 = ____

Answer:

Explanation:

25 = 2 tens and 5 ones

20 = 2 tens

when adding 20 + 25

we add the tens and keep the ones constant as their is no ones place in the second addend

(2 tens ) + (2 tens+ 5 ones) = (2+ 2) tens + 5 ones

4 tens + 5 ones = 45

20 + 25 = 45

Question 9.

49 + 30 = _____

Answer:

Explanation:

49 = 4 tens and 9 ones

30 = 3 tens

when adding 49 + 30

we add the tens and keep the ones constant as their is no ones place in the second addend

(4 tens + 9 ones) + 3 tens = (4+ 3) tens + 9 ones

7 tens + 9 ones = 79

49 + 30 =79

Question 10.

81 + 8 = _____

Answer:

Explanation:

81 = 8 tens and 1 ones

8 = 8 ones

when adding 81 + 8

we add the ones and keep the tens constant as their is no tens place in the second addend

(8 tens + 1 ones) + 8 ones = 8 tens +(8+1)ones

8 tens + 9 ones

81 + 8 = 89.

**Problem Solving**

Solve. Draw or write to explain.

Question 11.

Maria has 21 marbles. She buys a bag of 20 marbles. How many marbles does Maria have now?

______ marbles

Answer:

Number of marbles Maria had = 21

Number of marbles Maria bought = 20

Total number of marbles Maria have now = 21 + 20 = 41.

Question 12.

**WRITE**

Write a story problem about 40 apples and 17 pears.

Answer:

**Lesson Check**

Question 1.

What is the sum? Write the number.

62 + 30 = _____

Answer:

62 + 30 = 92

Explanation:

62 = 6 tens and 2 ones

30 = 3 tens

when adding 62 + 30

we add the tens and keep the ones constant as their is no ones place in the second addend

6 tens + 2 ones + 3 tens = (6 + 3) tens + 2 ones

9 tens + 2 ones = 92

Question 2.

What is the sum? Write the number.

37 + 2 = _____

Answer:

37 + 2 = 39

Explanation:

37 = 3 tens and 7 ones

2 = 2 ones

when adding 37 + 2

we add the ones and keep the tens constant as their is no tens place in the first addend

3 tens + 7 ones + 2 ones = 3 tens +(7 + 2)ones

3 tens + 9 ones = 39

37 + 2 = 39

**Spiral Review**

Question 3.

Write two ways to make 15.

____ + ____ = 15

_____ + ____ = 15

Answer:

10 + 5 = 15

3 + 12 = 15

Question 4.

What number does the model show?

______

Answer:

The number represented in the model is 103

10 tens and 3 ones = 103

Explanation

In the model show

lines represents tens

dot represents ones

There are 10 line and 3 dots

100 + 3 = 103.

### Lesson 8.6 Make Ten to Add

**Essential Question** How can making a ten help you add a two-digit number and a one-digit number?

**Listen and Draw**

Use . Draw to show how you can find the sum.

21 + 6 = _____

Answer:

21 + 6 = 27

**MATHEMATICAL PRACTICES**

Use Tools Explain how your model shows the sum of 21 + 6.

Answer:

21 + 6 = 27

**Share and Show**

Use . Draw to show how you make a ten. Find the sum.

Question 1.

49 + 3 = ?

_____ + ____ = _____

So, 49 + 3 = ____

Answer:

49 + 3 =

50 + 2 = 52

49 + 3 = 52

Explanation:

49 + 3 = 52

while adding the ones 9 + 3 we are borrowing 1 ones from 3 to make it tens.

Remaining 2 ones are added to the tens.

49 + 1 + 2 = 50 + 2 = 52.

**On Your Own**

**MATHEMATICAL PRACTICE** Use a Concrete Model

Use . Draw to show how you make a ten. Find the sum.

Question 2.

39 + 7 = _____

Answer:

Explanation:

39 + 7 = 46

while adding the ones 9 + 7 we are borrowing 1 ones from 7 to make it tens.

Remaining 6 ones are added to the tens.

39 + 1 + 6

= 40 + 6

= 46.

Question 3.

72 + 9 = _____

Answer:

Explanation:

72 + 9

while adding the ones 2 + 9 we are borrowing 8 ones from 9 ones to make it tens.

Remaining 1 ones are added to the tens.

72 + 9

=72 + 8 + 1

= 80 + 1

= 81.

Question 4.

58 + 5 = ____

Answer:

Explanation:

58 + 5 = 63

while adding the ones 8 + 5 we are borrowing 2 ones from 5 to make it tens.

Remaining 3 ones are added to the tens.

58 + 5

=58 + 2 +3

= 60 + 3

= 63

**THINK SMARTER** Solve. Write the numbers.

Question 5.

So, 46 + 7 = _____

Answer:

46 + 7 = 53

Question 6.

So, 53 + 8 = _____

Answer:

53 + 8 = 53 + 7 + 1 = 60 +1 = 61

**Problem Solving • Applications**

Choose a way to solve. Draw or write to show your work.

Question 7.

**THINK SMARTER**

Koby puts 24 daisies and 8 tulips in a vase. How many flowers are in the vase?

______ flowers

Answer:

Number of Daisies flower = 24

Number of Tulips flowers = 8

Total number of flowers = 24 + 8

24 + 6 + 2

30 + 2

32.

Question 8.

GO DEEPER

There are 27 ducklings in the water. 20 of them come out of the water. How many ducklings are still in the water?

______ ducklings

Answer:

Total Number of Ducklings in the water = 27

Number of ducklings came out of water = 20

Number of ducklings still in water = 27 – 20 = 7

7 ducklings are still in the water.

Question 9.

Write the missing addend.

Answer:

46 + 6 = 52

Explanation:

To find the missing addend

we need to subtract the 1st addend from the sum

52 – 46 =6.

6 is the missing addend.

Question 10.

**THINK SMARTER**

Use the model. Draw to show how to make a ten.

Answer:

Explanation:

58 + 5 = 63

while adding the ones 8 + 5 we are borrowing 2 ones from 5 to make it tens.

Remaining 3 ones are added to the tens.

58 + 5

=58 + 2 +3

= 60 + 3

= 63

**TAKE HOME ACTIVITY** • Ask your child to explain how to find the sum for 25 + 9.

### Make Ten to Add Homework & Practice 8.6

Use . Draw to show how you make a ten. Find the sum.

Question 1.

26 + 5 = ______

Answer:

Explanation:

26 + 5

while adding the ones 6 + 5 we are borrowing 4 ones from 5 to make it tens.

Remaining 1 ones are added to the tens.

26 + 5

26 + 4 + 1

30 + 1

31

Question 2.

68 + 4 = _____

Answer:

Explanation:

68 + 4 = 72

while adding the ones 8 + 4 we are borrowing 2 ones from 4 to make it tens.

Remaining 2 ones are added to the tens.

68 + 4

68 + 2 + 2

70 + 2

72

**Problem Solving**

Choose a way to solve. Draw or write to show your work.

Question 3.

Debbie has 27 markers. Sal has 9 markers. How many markers do they have?

_______ markers

Answer:

Number of markers with Debbie = 27

Number of markers with Sal = 9

Total number of markers both have = 27 + 9 = 36.

36 markers.

Question 4.

**WRITE**

Use words or pictures to explain how to solve 44 + 7.

Answer:

Explanation:

44 + 7

while adding the ones 4 + 7 we are borrowing 6 ones from 7 ones to make it tens.

Remaining 1 ones are added to the tens.

44 + 7

44 + 6 + 1

50 + 1

51

**Lesson Check**

Question 1.

What is the sum? Write the number.

47 + 6 = _____

Answer:

Explanation:

47 + 6

while adding the ones 7 + 6 we are borrowing 3 ones from 6 ones to make it tens.

Remaining 3 ones are added to the tens.

47 + 6

47 + 3 + 3

50 + 3

53

Question 2.

What is the sum? Write the number.

84 + 8 = _____

Answer:

Explanation:

84 + 8

while adding the ones 4 + 8 we are borrowing 6 ones from 8 ones to make it tens.

Remaining 2 ones are added to the tens.

84 + 8

=84 + 6 + 2

= 90 + 2

= 92

**Spiral Review**

Question 3.

What number does the model show? Write the number.

Answer:

11 tens + 4 ones

110 + 4

114

Question 4.

Write a number to make the sentence true.

5 + 4 = 10 – ______

Answer:

5 + 4 = 10 – 1

### Lesson 8.7 Use Place Value to Add

**Essential Question** How can you model tens and ones to help you add two-digit numbers?

**Listen and Draw**

Model the problem with . Draw a quick picture to show your work.

**MATHEMATICAL PRACTICES**

Describe How many tens? How many ones? How many in all?

Answer:

**Share and Show**

Draw a quick picture. Use tens and ones to add.

Question 1.

Answer:

**On Your Own**

**MATHEMATICAL PRACTICE** Make Connections Draw a quick picture. Use tens and ones to add.

Question 2.

Answer:

Question 3.

Answer:

Question 4.

**THINK SMARTER**

Solve.

Answer:

Question 5.

Answer:

Question 6.

**THINK SMARTER**

Draw a quick picture to solve. Han has 37 shells. Jonah had 15 shells. How many shells do they have?

_______

Answer:

Number of shells Han has = 37

Number of shells Jonah has =15

Total number of shells both has = 37 + 15 = 52

**Problem Solving • Applications**

Question 7.

**THINK SMARTER**

Draw a quick picture to solve. Kim has 24 marbles. Al has 47 marbles.How many marbles do they have?

______ marbles

Answer:

Number of marbles Kim has = 24

Number of marbles Al has =47

Total number of marbles both have = 24 + 47 = 71

Question 8.

**GO DEEPER**

Choose two addends from 11 to 49. Draw them. Add in any order to solve.

Answer:

35 and 45 are the two addends

Question 9.

**THINK SMARTER**

Write the addition that the model shows. Solve.

Answer:

Explanation:

There are 5 tens and 2 ones in the first addend and 1 tens and 5 ones in the second addend

(5 + 1) tens + (2 + 5 )ones = 6 tens + 7 ones = 60 + 7 = 67.

**TAKE HOME ACTIVITY** • Write the numbers 42 and 17. Have your child tell how to find the sum by adding the tens and ones.

### Use Place Value to Add Homework & Practice 8.7

Draw a quick picture. Use tens and ones to add.

Question 1.

Answer:

Question 2.

Answer:

**Problem Solving**

Question 3.

Write two addition sentences you can use to find the sum. Then solve.

Answer:

Question 4.

**WRITE**

Write and solve a story problem to add 12 and 18.

Answer:

Ram has 12 five star chocolates. Ravi has 18 much chocolates. How many chocolates does they have..?

Answer:

Number of chocolates Ram have = 12

Number of chocolates Ravi have =18

Total number of chocolates does both have = 12 + 18 = 30.

**Lesson Check**

Question 1.

What is the sum? Write the number.

Answer:

Question 2.

What is the sum? Write the number.

Answer:

**Spiral Review**

Question 3.

I have 28 cubes. How many tens and ones can I make?

_____ tens ____ ones

_____ ten _____ ones

Answer:

You can make as below

**2** tens **8** ones

**1** ten **18** ones

Question 4.

What is the sum? Write the number.

Answer:

### Lesson 8.8 Problem Solving • Addition Word Problems

**Essential Question** How can drawing a picture help you explain how to solve an addition problem?

Kelly gets 6 new toy cars. He already has 18 toy cars. How many does he have now?

Show how to solve the problem.

____________________

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_____________________

Answer:

Number of toy cars Kelly got = 6

Number of toy cars Kelly had = 18

Total number of toy cars with Kelly = 18 + 6 = 24.

**HOME CONNECTION** • Being able to show and explain how to solve a problem helps your child build on their understanding of addition.

**Try Another Problem**

Draw and write to solve. Explain your reasoning.

Question 1.

Aisha picks 60 blueberries to make a pie. Then she picks 12 more to eat. How many blueberries does Aisha pick?

Answer:

Number of blueberries Aisha picked to make a pie = 60

Number of blueberries Aisha picked to eat = 12

Total number of blueberries Aisha picked = 60 +12 = 72.

Question 2.

Yuri collects 21 cans for the school food drive. Leo collects 36 cans. How many cans do Yuri and Leo collect?

Answer:

Number of cans Yuri collects from school food drive =21

Number of cans Leo collects = 36

Total number of cans Yuri and Leo collects = 21 + 36 =57.

**MATHEMATICAL PRACTICES**

Explain the addition strategy you used to solve Exercise 1.

Answer:

**Share and Show**

**MATHEMATICAL PRACTICE** Use Reasoning Draw and write to solve.

Question 3.

Tyra sees 48 geese in the field. Then she sees 17 more geese in the sky. How many geese does Tyra see?

______ geese

Answer:

Number of geese Tyra sees in the field = 48

Number of geese Tyra sees in the sky = 17

Total number of geese Tyra sees = 48 + 17 = 65.

Question 4.

Jade paints 35 circles and 45 triangles in art class. How many shapes does Jade paint?

_____ shapes

Answer:

Number of circles Jade paints = 35

Number of triangles Jade paints = 45

Total number of shapes Jade paints = 35 +45 =80

Question 5.

**THINK SMARTER**

It takes 10 hops to get across the yard. How many hops does it take to get across the yard and back?

_____ hops

Answer:

Number of hops to get across the yard = 10

Number of hops to get across the yard and back the yard = 2 times the hops to gt across the yard

10 + 10 = 20.

**On Your Own**

Choose a way to solve. Draw or write to explain.

Question 6.

**THINK SMARTER**

Julian sells 3 books of tickets for the school fair. Each book has 20 tickets. How many tickets does Julian sell?

_____ tickets

Answer:

Number of tickets in each book = 20 tickets

Number of books of tickets Julian sell = 3

Total number of tickets Julian sell = 3 × 20

60 tickets.

Question 7.

**GO DEEPER**

I have some red roses and pink roses. I have 14 red roses. I have 8 more pink roses than red roses. How many roses do I have?

______ roses

Answer:

Total number of red roses i have = 14

Number of pink roses are 8 more than red roses = 8 +14 = 22

Total number of roses i have = 14 + 22 = 36.

I have 36 roses.

Question 8.

**THINK SMARTER+**

Ella sees 27 . She sees 28 . How many does Ella see? Circle the number that makes this sentence true.

Answer:

Number of Ella sees = 27

Number of Ella sees = 28

Total number of Ella sees = 27 + 28 = 55

**TAKE HOME ACTIVITY** • Ask your child to solve 16 + 7, 30 + 68, and 53 + 24. Ask him or her to explain how they solved each problem.

### Problem Solving • Addition Word Problems Homework & Practice 8.8

Draw and write to solve. Explain your reasoning.

Question 1.

Jean has 10 fish. She gets 4 more fish. How many fish does she have now?

____________________________

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_____________________________

_____ fish

Answer:

Number of fish Jean has = 10

Number of more fish she gets = 4

Total number of fish she have = 10 + 4 = 14

Explanation:

Given

Jean has 10 fish = 10

She gets more fish = 4

now on adding the both we get the total fish she have = 10 + 4 = 14.

Question 2.

Courtney buys 2 bags of apples. Each bag has 20 apples. How many apples does she buy?

____________________________

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_____________________________

_____ apples

Answer:

Number of bags of apples Courtney buys = 2

Number of apples in each bag = 20

Total number of apples she buy = 2 × 20 = 40

20 + 20 = 40 apples.

Question 3.

John bakes 18 blueberry muffins and 12 banana muffins for the bake sale. How many muffins does he bake?

_____________________________

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_____________________________

______ muffins

Answer:

Number of blueberry muffins John bakes = 18

Number of banana muffins John bakes = 12

Total number of muffins John bakes = 18 + 12 = 30 muffins.

Question 4.

**WRITE**

Draw a picture to show how to find 12 + 37.

Answer:

**Lesson Check**

Question 1.

Amy has 9 books about dogs. She has 13 books about cats. How many books does she have about dogs and cats? Solve. Show your work. Write the number.

______ books

Answer:

Number of books about dogs Amy has = 9

Number of books about cats Amy has = 13

Total number of books about dogs and cats Amy has = 9 + 13 = 21 books.

**Spiral Review**

Question 2.

What is the sum for 4 + 2 + 4? Write the number.

______

Answer:

4 + 2 + 4 = 10

Question 3.

Solve. Use the ten frame to make a ten to help you subtract. Ray has 14 pens. 8 are black. The rest are blue. How many pens are blue?

______ blue pens

Answer:

Total number of pens = 14

Number of black pens = 8

Number of blue tens = total – black pens

14 – 8 = 6

8 + 6 = 14.

### Lesson 8.9 Related Addition and Subtraction

**Essential Question** How can you use a hundred chart to show the relationship between addition and subtraction?

**Listen and Draw**

Use the hundred chart to solve the problems.

**MATHEMATICAL PRACTICES**

Apply Describe how you can use a hundred chart to find the sum and the difference.

Answer:

**Share and Show**

Use the hundred chart to add and subtract. Count up and back by tens.

Question 1.

56 + 20 = _____

76 – 20 = ______

Answer:

Explanation:

The given question is a tens count addition and subtraction.

first sentence = 56 + 20 = 76

it is represented with blue color. its a down flow. So, from 56 we count 2 tens down.

Second sentence = 76 – 20 = 56

it is represented with orange color. its a up flow. So, from 76 we count 2 tens up.

Question 2.

48 + 50 = _____

98 – 50 = _____

Answer:

Explanation:

The given question is a tens count addition and subtraction.

first sentence = 48 + 50 = 98

it is represented with blue color. its a down flow. So, from 48 we count 5 tens down.

Second sentence = 98 – 50 = 48

it is represented with orange color. its a up flow. So, from 98 we count 5 tens up.

**On Your Own**

Answer:

Explanation:

The given question is a tens count addition and subtraction.

first sentence = 28 + 60 = 88

it is represented with blue color. its a down flow. So, from 28 we count 6 tens down.

Second sentence = 88 – 60 = 28

it is represented with orange color. its a up flow. So, from 88 we count 6 tens up.

**MATHEMATICAL PRACTICE** Look for a Pattern Use the hundred chart to add and subtract. Count up and back by tens.

Question 3.

36 + 30 = _____

66 – 30 = ______

Answer:

Explanation:

The given question is a tens count addition and subtraction.

first sentence = 36 + 30 = 66

it is represented with blue color. its a down flow. So, from 36 we count 3 tens down.

Second sentence = 66 – 30 = 36

it is represented with orange color. its a up flow. So, from 66 we count 3 tens up.

Question 4.

73 + 10 = _____

83 – 10 = ______

Answer:

Explanation:

The given question is a tens count addition and subtraction.

first sentence = 73 + 10 = 83

it is represented with blue color. its a down flow. So, from 73 we count 1 tens down.

Second sentence = 83 – 10 = 73

it is represented with orange color. its a up flow. So, from 83 we count 1 tens up.

Question 5.

25 + 70 = _______

95 – 70 = ______

Answer:

Explanation:

The given question is a tens count addition and subtraction.

first sentence = 25 + 70 = 95

it is represented with blue color. its a down flow. So, from 25 we count 7 tens down.

Second sentence = 95 – 70 = 25

it is represented with orange color. its a up flow. So, from 95 we count 7 tens up.

Question 6.

18 + 40 = ______

58 – 40 = ______

Answer:

Explanation:

The given question is a tens count addition and subtraction.

first sentence = 18 + 40 = 58

it is represented with blue color. its a down flow. So, from 18 we count 4 tens down.

Second sentence = 58 – 40 = 18

it is represented with orange color. its a up flow. So, from 58 we count 4 tens up.

Question 7.

**THINK SMARTER**

Solve. There are 73 bees in a hive. 10 bees fly away. Then 10 more bees fly into the hive. How many bees are in the hive now?

______ bees

Answer:

Total number of bees in hive = 73

Number of bees flew away = 10

Number of bees flew back into the hive = 10

Total number of bees in the hive = 73 – 10 = 63 + 10 = 73.

Explanation:

The given question is a tens count addition and subtraction.

first sentence = 73 +10 = 83

it is represented with blue color. its a down flow. So, from 73 we count 1 tens down.

Second sentence = 83 – 10 = 73

it is represented with orange color. its a up flow. So, from 83 we count 1 tens up.

**Problem Solving • Applications**

Solve. Draw or write to show your work.

Question 8.

**THINK SMARTER**

There are 38 ants on a rock. 10 move to the grass. 10 walk up a tree. How many ants are on the rock now?

______ ants

Answer:

Total number of ants on the rock = 38

Number of ants move to grass = 10

Number of ants walk up the tree = 10

Number of ants on the rock = 38 – 10 – 10 = 18 ants.

Question 9.

**GO DEEPER**

There are 27 birds at the park. 50 more birds come. Then 50 fly away. How many birds are at the park now?

_______ birds

Answer:

Number of birds in the park = 27

Number of birds came into the park = 50

Number of birds flew away =50

Total number of birds in the park = 27 + 50 = 77 – 50 = 27.

Explanation:

The given question is a tens count addition and subtraction.

first sentence = 27+ 50 = 77

it is represented with blue color. its a down flow. So, from 27 we count 5 tens down.

Second sentence = 77 – 50 = 27

it is represented with orange color. its a up flow. So, from 77 we count 5 tens up.

Question 10.

**THINK SMARTER**

Match the math sentences that count up and back by tens.

Answer:

**TAKE HOME ACTIVITY** • On slips of paper, write 36 + 40 and 76 − 40. Ask your child to explain how to use the hundred chart to count up and back by tens to find the sum and the difference.

### Related Addition and Subtraction Homework & Practice 8.9

Use the hundred chart to add and subtract. Count up and back by tens.

Question 1.

16 + 60 = _____

76 – 60 = ______

Answer:

Explanation:

The given question is a tens count addition and subtraction.

first sentence = 16 + 60

it is represented with blue color. its a down flow. So, from 16 we count 6 tens down.

Second sentence = 76 – 60

it is represented with orange color. its a up flow. So, from 76 we count 6 tens up.

Question 2.

61 + 30 = ______

91 – 30 = ______

Answer:

Explanation:

The given question is a tens count addition and subtraction.

first sentence = 61 + 30

it is represented with blue color. its a down flow. So, from 61 we count 3 tens down.

Second sentence =91 – 30

it is represented with orange color. its a up flow. So, from 91 we count 3 tens up.

Question 3.

64 + 20 = _____

84 – 20 = ______

Answer:

Explanation:

The given question is a tens count addition and subtraction.

first sentence = 64 + 20

it is represented with blue color. its a down flow. So, from 64 we count 2 tens down.

Second sentence = 84 – 20

it is represented with orange color. its a up flow. So, from 84 we count 2 tens up.

**Problem Solving**

Choose a way to solve. Draw or write to show your work.

Question 4.

There are 53 leaves in a tree. 20 leaves blow away. How many leaves are left in the tree?

______ leaves

Answer:

Total number of leaves on the tree = 53 leaves

Number of leaves blow away = 20

Number of leaves left on the tree = 53 – 20 = 33

33 leaves.

Question 5.

**WRITE**

Write a number sentence to subtract 3 tens from 93.

Answer:

93 -30 = 63.

Explanation:

The given question is a tens count subtraction.

First sentence = 93 – 30 = 63.

it is represented with orange color. its a up flow. So, from 93 we count 3 tens up.

**Lesson Check**

Question 1.

What is 78 − 20? Write the number.

______

Answer:

78 – 20 = 58

Explanation:

First sentence = 78 – 20

it is represented with orange color. its a up flow. So, from 78 we count 2 tens up.

Question 2.

What is 37 + 50? Write the number.

______

Answer:

37 + 50 = 87

Explanation:

The given question is a tens count addition and subtraction.

first sentence = 37 + 50

it is represented with blue color. its a down flow. So, from 37 we count 5 tens down.

**Spiral Review**

Question 3.

Use the model. What is the difference of 7 − 3? Write the number.

7 – 3 = ______

Answer:

7 – 3 = 4

Explanation:

First sentence = 7 – 3 = 4

it is represented with orange color. its a backward flow. So, from 7 we count 3 ones back to reach 4

Question 4.

What is the sum for 0 + 7? Write the number.

______

Answer:

Explanation:

The given question is a tens count addition and subtraction.

first sentence = 0 + 7 = 7

it is represented with blue color. its a forward flow. So, from 1 we count 6 ones to reach 7.

### Lesson 8.10 Practice Addition and Subtraction

**Essential Question** What different ways can you use to add and subtract?

**Listen and Draw**

Draw to show the problem. Then solve.

**MATHEMATICAL PRACTICES**

Describe How did you solve the problem?

Answer:

**Model and Draw**

What ways have you learned to add and subtract?

Answer:

**Share and Show**

Add or subtract.

Question 1.

30 + 60 = ______

Answer:

Explanation:

30 = 3 tens

60 = 6 tens

when adding 30+60

we add the tens

3 tens + 6 tens = (3+6) tens

9 tens

90.

Question 2.

73 + 5 = ______

Answer:

Explanation:

73 = 7 tens and 3 ones

5 = 5 ones

when adding 73 + 5

we add the ones and keep the tens constant as their is no tens place in the second addend

7 tens + 3 ones + 5 ones = 7 tens +(3 + 5) ones

7 tens + 8 ones

70 + 8 = 78.

Question 3.

10 – 4 = _____

Answer:

10 – 4 = 6

Explanation:

We subtract the subtrahend from the minuend to get the difference.

10 – 4 = 6

10 is minuend and 40 is subtrahend and 6 is difference of both

10 – 4 = 6

Question 4.

29 + 4 = _____

Answer:

Explanation:

29 + 4

while adding the ones 9 + 4 we are borrowing 1 ones from 4 ones to make it tens.

Remaining 3 ones are added to the tens.

29 + 4

29 +1 +3

30 + 3

33.

Question 5.

9 + 9 = ____

Answer:

Explanation:

9 + 9

while adding the ones 9 +9 we are borrowing 1 ones from 9 ones to make it tens.

Remaining 8 ones are added to the tens.

9 + 9

9 + 1 + 8

10 + 8

18.

Question 6.

5 + 6 = ____

Answer:

Explanation:

5 + 6

while adding the ones 5 + 6 we are borrowing 5 ones from 6 ones to make it tens.

Remaining 1 ones are added to the tens.

5 + 6

5 + 5 + 1

10 + 1

11.

Question 7.

25 + 54 = _____

Answer:

Question 8.

15 – 8 = ______

Answer:

7 + 8 = 15

15 – 8 = 7

Explanation:

We subtract the subtrahend from the minuend to get the difference.

15 – 8 = 7

15 is minuend and 8 is subtrahend and 7 is difference of both

15 – 8 = 7

7.

Question 9.

40 + 10 = _____

Answer:

Question 10.

40 – 10 = _____

Answer:

Explanation:

We subtract the subtrahend from the minuend to get the difference.

40 – 10 = 30

40 is minuend and 10 is subtrahend and 30 is difference of both

ONE line represents tens

1 line = 10

40 – 10 = 30

30 = 3 lines

Question 11.

14 – 7 = _____

Answer:

Explanation:

We subtract the subtrahend from the minuend to get the difference.

14 – 7 = 7

14 is minuend and 7 is subtrahend and 7 is difference of both

14 – 7

7.

Question 12.

90 – 70 = _____

Answer:

Explanation:

We subtract the subtrahend from the minuend to get the difference.

90 – 70

90 is minuend and 70 is subtrahend and 20 is difference of both

ONE line represents tens

1 line = 10

90 – 70 = 20

20.

Question 13.

86 + 12 = _____

Answer:

Question 14.

1 + 9 = _____

Answer:

Question 15.

6 + 7 = _____

Answer:

Explanation:

6 + 7 = 13

while adding the ones 6 + 7 we are borrowing 4 ones from 7 ones to make it tens.

Remaining 3 ones are added to the tens.

6+7

6 + 4 + 3

10 + 3

13.

Question 16.

9 – 2 = _____

Answer:

7 + 2 = 9

9 – 2 = 7

Explanation:

We subtract the subtrahend from the minuend to get the difference.

9 – 2

9 is minuend and 2 is subtrahend and 7 is difference of both

9 – 2

7.

Question 17.

8 + 31 = _____

Answer:

Explanation:

31 = 3 tens and 1 ones

8 = 8 ones

when adding 8 +31

we add the ones and keep the tens constant as their is no tens place in the first addend

8 ones + 3 tens + 1 ones = 3 tens +(8 + 1) ones

3 tens + 9 ones

30 + 9 = 39.

Question 18.

50 + 11 = _____

Answer:

Explanation:

50 = 5 tens

11 = 1 tens and 1 ones

when adding 50 + 11

we add the tens and keep the ones constant as their is no ones place in the second addend

5 tens + 1 tens + 1 ones = (5 + 1) tens +1 ones

6 tens + 1 ones

60 + 1 = 61.

**On Your Own**

**MATHEMATICAL PRACTICE** Use Repeated Reasoning Add or subtract.

Question 19.

Answer:

12 – 3 = 9

9 + 3 = 12

Explanation:

We subtract the subtrahend from the minuend to get the difference.

12 – 3 = 9

12 is minuend and 3 is subtrahend and 9 is difference of both

12 – 3 = 9.

Question 20.

Answer:

Question 21.

Answer:

Question 22.

Answer:

Question 23.

Answer:

Question 24.

Answer:

Explanation:

16 + 7

while adding the ones 6 + 7 we are borrowing 4 ones from 7 ones to make it tens.

Remaining 3 ones are added to the tens.

16 + 7

16 + 4 + 3

20 + 3

23.

Question 25.

Answer:

Explanation:

Any number subtracted from the the number itself gives the difference zero.0

Question 26.

Answer:

Explanation:

3 + 8

while adding the ones 3 + 8 we are borrowing 7 ones from 1 ones to make it tens.

Remaining 1 ones are added to the tens.

3 + 8

3 + 7 + 1

10 + 1

11.

Question 27.

Answer:

Question 28.

Answer:

Explanation:

We subtract the subtrahend from the minuend to get the difference.

60 – 30 = 30

60 is minuend and 30 is subtrahend and 30 is difference of both

ONE line represents tens

1 line = 10

60 – 30 = 30

30.

Question 29.

Answer:

Question 30.

Answer:

Question 31.

Answer:

Question 32.

Answer:

Question 33.

Answer:

Question 34.

Answer:

Solve. Write or draw to explain.

Question 35.

**THINK SMARTER**

Lara collects 8 more stamps than Samson. Samson collects 39 stamps. How many stamps does Lara collect?

______ stamps

Answer:

Number of Stamps Samson collect = 39

Number of Stamps Lara Collect = 8 more than Samson = 8 + 39 = 47

**Problem Solving • Applications**

Solve. Write or draw to explain.

Question 36.

**THINK SMARTER**

Jane drew some stars. Then she drew 9 more stars. Now there are 19 stars. How many stars did Jane draw first?

Answer:

Jane drew some stars =x

Jane drew again some more stars = x + 9

Now total Number of stars = 19

Number of stars Jane draw first = x

x + 9 = 19

x =19 – 9 = 10

Number of stars Jane draw first = 10

Question 37.

**THINK SMARTER**

Adel drew 10 more stars than Charlie. Charlie drew 24 stars. How many stars did Adel draw?

______ stars

Answer:

Number of stars Charlie drew = 24 stars.

Adel drew 10 more stars than Charlie. = 24 + 10 = 34

Number of stars adel draw = 34

Question 38.

**GO DEEPER**

Write three ways to get a sum of 49.

Answer:

20 + 29 = 49

35 + 14 = 49

40 + 9 = 49

Question 39.

**THINK SMARTER**

Find the sum of 23 and 30. Use any way to add.

23 + 30 = _______

Explain how you solved the problem.

Answer:

23 + 30 = 53

30 + 23 = 53

Explanation :

Whatever may be the order of addends but the sum always remains the same .

**TAKE HOME ACTIVITY** • Have your child explain how he or she solved Exercise 36.

### Practice Addition and Subtraction Homework & Practice 8.10

Add or subtract.

Question 1.

Answer:

Question 2.

Answer:

Question 3.

Answer:

Question 4.

Answer:

Question 5.

Answer:

Question 6.

Answer:

Question 7.

Answer:

Question 8.

Answer:

Question 9.

Answer:

Question 10.

Answer:

**Problem Solving**

Solve. Write or draw to explain.

Question 11.

Andrew read 17 pages of his book before dinner. He read 9 more pages after dinner. How many pages did he read?

______ pages

Answer:

Number of pages Andrew read before dinner = 17

Number of pages Andrew read after dinner = 9 more = 9 + 17 = 26

Number of pages Andrew read = 17 + 26 = 43

Question 12.

**WRITE**

Write two ways you could use to find 5 + 8.

Answer:

5 + 8 = 13

8 + 5 = 13

Explanation :

Whatever may be the order of addends but the sum always remains the same .

**Lesson Check**

Question 1.

What is the sum of 20 + 18? Write the sum.

20 + 18 = ______

Answer:

20 + 18 = 38

Explanation :

Adding addend 20 and 18 gives the sum 38 .

Question 2.

What is the difference of 90 − 50? Write the difference.

90 – 50 = ______

Answer:

90 – 50 = 40

Explanation :

the Minuend 90 is subtrahend with 50 gives the difference 40

**Spiral Review**

Question 3.

Use the model. What number sentence does this model show? Write the number sentence that the model shows.

Answer:

10 + 3 = 13

Question 4.

Solve. Mo had some toys. He gave 6 away. Now he has 6 toys. How many toys did Mo start with?

______ toys

Answer:

Number of toys with Mo = x

Number of toys Mo gave = 6 away = x – 6

Number of toys with Mo now = 6

x – 6 = 6

x = 6 + 6 = 12

Number of toys Mo started with = 12

### Two-Digit Addition and Subtraction Review/Test

Question 1.

Write each addition or subtraction problem in the box below the answer.

Answer:

Question 2.

Choose all the ways that name the model.

Answer:

Question 3.

Sasha has 70 stickers. She uses 40 of them. How many stickers are left? Show your work.

________ stickers

Answer:

Number of stickers Sasha has = 70

Number of stickers she used = 40

Number of stickers left = 70 – 40 = 30.

Question 4.

**THINK SMARTER+**

Use the hundred chart to add. Count on by ones or tens.

37 + 5 = ______

Explain how you used the chart to find the sum.

Answer:

37 + 5 = 42.

Sum = 42.

Question 5.

Use the model. Draw to show how to add the tens.

Answer:

Question 6.

Use the model. Draw to show how to make a ten.

Answer:

Question 7.

Write the addition sentence that the model shows. Solve.

Answer:

Question 8.

What is the difference?

Answer:

Question 9.

What is the sum?

Answer:

Question 10.

Luis has 16 .

He has 38

1.

How many leaves does Luis have? Circle the number

that makes the sentence true.

Luis has 2 leaves.

Answer:

Number of leaves Luis has = 16

Number of leaves = 38

Total number of leaves Luis have = 16 + 38 = 54

Question 11.

Match the math sentences that count up and back by tens.

Answer:

Question 12.

**GO DEEPER**

Find the sum of 62 and 15. Use any way to add.

62 + 15 = _______

Explain how you solved the problem.

Answer: