Solve

Question 1.
17 + 2 = 19
2 + 17 = ____
17 + 2 = 19
2 + 17 = 19

Explanation:
The order of the addends does not matter
The sum does not change
So, 17 + 2 = 2 + 17.

Question 2.
8 + 1 = ___
1 + 8 = ____
8 + 1 = 9
1 + 8 = 9

Explanation:
The order of the addends does not matter
The sum does not change
So, 8 + 1 = 1 + 8.

Question 3.
12 + 5 = ___
5 + 12 = ____
12 + 5 = 17
5 + 12 = 17

Explanation:
The order of the addends does not matter
The sum does not change
So, 12 + 5 = 5 + 12.

Question 4.
3 + 5 = ___
5 + 3 = ___
3 + 5 = 8
5 + 3 = 8

Explanation:
The order of the addends does not matter
The sum does not change
So, 3 + 5 = 5+3.

Question 5.  Explanation:
The order of the addends does not matter
The sum does not change
So, 10 + 5 = 5 + 10.

Question 6.  Explanation:
The order of the addends does not matter
The sum does not change
So, 7 + 1 = 1 + 7.

Question 7.  Explanation:
The order of the addends does not matter
The sum does not change
So, 3 + 13 = 13 + 3.

Write the missing number.

Question 8.
12 + 3 = 3 + ___
12 + 3 = 3 +12

Explanation:
The order of the addends does not matter
The sum does not change
The missing number is 12
So, 12 + 3 = 3 + 12.

Question 9.
___ + 6 = 6 + 13
13 + 6  = 6 +13

Explanation:
The order of the addends does not matter
The sum does not change
The missing number is 13
So, 13 + 6 = 6 +13.

Question 10.
1 + ___ = 8 + 1
1 + 8 = 8 + 1

Explanation:
The order of the addends does not matter
The sum does not change
The missing number is 8
So, 1 + 8 = 8 + 1.

Question 11.
Chen and Alex see 1 cat and 3 dogs. They count to see how many animals in all. Chen counts the dogs first and then the cat. Alex counts the cat first and then the dogs. Are the sums different? Explain.