Find the Answer by Doing the Inverse Operation

Did you know that we can check answers to addition questions using subtraction, and check subtraction answers using addition?

This is called the inverse operation. Clever!

In this activity, we are going to practise checking our answers using the inverse operation.

Example

Look at this addition question.

650 + 125 =

We can probably work out the answer mentally.

650 + 125 = 775

It is always worth checking our answers.  This is quite an easy example, but sometimes we'll have much more difficult questions to answer, so it's worth having a good method for checking!

Let's check

The opposite (inverse) of addition is subtraction.

So we work out 775 - 125 = 650

Let's have a look at another one using subtraction

630 - 220 = 410

Now, let's use the inverse operation to check we have the correct answer.

220 + 410 = 630

Now it's your turn to have a go at using the inverse operation to check some answers - good luck!