Check subtractions using inverse operations
for 5th grade

How to use inverse operations to check subtractions

In this topic you are asked to select the correct inverse operation to use to check the given subtraction sum.

Inverse operations are pairs of operations that "undo" each other. For example, addition and subtraction are inverse operations, as are multiplication and division. To use inverse operations to check subtractions, you can perform the opposite operation to the subtraction, which should result in the original number you started with.

Let's say you have answered the subtraction problem: 25 - 7 and decided the answer is 18.

To check this problem using inverse operations, you can perform the opposite operation to subtraction, which is addition. So, you can add 7 to the answer 18 to get back to the original number:

25 - 7 = 18

18 + 7 = 25

If the answer you get from adding the two numbers is the same as the number you started with (in this case, 25), then you know that your original subtraction problem was correct.

A more complex subtraction might be 72 - 45

To check this problem using inverse operations, you can perform the inverse operation, addition. So, you can add 45 to your answer to get back to the original number:

72 - 45 = 27

27 + 45 = 72

Notes on the topic: Check subtractions using inverse operations

In each question you are given a subtraction equation. You are asked to choose the inverse equation that will confirm the subtraction is correct.