Inverse operations

Using inverse operations to check calculations

Name:

Date:

Try each question. If you're stuck, leave it and come back. The answer key is on the last page.

1
Check 25 + 18 = 43 using subtraction. 43 - 18 = ___ 43 - 18 = ___
Answer:
2
What is the inverse of addition? A) Addition B) Subtraction C) Multiplication D) Division
Answer:
3
True or false? If 36 + 14 = 50, then 50 - 14 = 36. A) True B) False
Answer:
4
Check 14 + 9 = 23 using subtraction. 23 - 9 = ___ 23 - 9 = ___
Answer:
5
Check 72 - 35 = 37 using addition. 37 + 35 = ___ 37 + 35 = ___
Answer:
6
What is the inverse of multiplication? A) Addition B) Subtraction C) Division D) Multiplication
Answer:
7
True or false? To check 6 × 4 = 24, we can do 24 ÷ 4 = 6. A) True B) False
Answer:
8
Use the inverse to find the missing number: ___ + 27 = 65 ___ + 27 = 65
Answer:
9
Which calculation checks that 48 ÷ 6 = 8? A) 48 - 6 = 42 B) 8 × 6 = 48 C) 8 + 6 = 14 D) 48 + 6 = 54
Answer:
10
Find the missing number using the inverse: 84 - ___ = 56 84 - ___ = 56
Answer:

Answer key

Inverse operations · for parents and teachers

1
25
43 - 18 = 25. The subtraction undoes the addition, giving back the other number.
2
Subtraction
Subtraction is the inverse of addition. They undo each other.
3
True
True. 50 - 14 = 36, which matches. Subtraction is the inverse of addition.
4
14
23 - 9 = 14. The inverse gives back the other addend.
5
72
37 + 35 = 72. Addition undoes subtraction, so we get back to 72.
6
Division
Division is the inverse of multiplication. They undo each other.
7
True
True. 24 ÷ 4 = 6, which gives back one of the factors.
8
38
65 - 27 = 38. Using the inverse (subtraction) finds the missing addend.
9
8 × 6 = 48
8 × 6 = 48 shows the division is correct, because multiplication undoes division.
10
28
84 - 56 = 28. The missing number is 28, because 84 - 28 = 56.