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## ​  Addition (+) and subtraction (-) are inverse operations.

This means that every addition is a subtraction in reverse, and every subtraction is an addition in reverse.

3 + 2 = 5

5 - 2 = 3

Notice how the same three numbers are used, but in the reverse order. This fact is very useful for checking your answer when calculating.

For example, you may perform the following subtraction:

584 - 408 = 176

To check that this is correct you can reverse the subtraction into an addition (which most people find easier than subtraction):

176 + 408 = 584

If you end up with the same three numbers, but in reverse order, you can be confident your subtraction was correct.

Multiplication (×) and division (÷) are inverse operations.

This means that every multiplication is a division in reverse, and every division is a multiplication in reverse.

5 × 2 = 10

10 ÷ 2 = 5

Notice how the same three numbers are used, but in the reverse order. This fact is very useful for checking your answer when calculating.

For example, you may perform the following division:

255 ÷ 3 = 85

To check that this is correct you can reverse the division into a multiplication (which most people find easier than division):

85 × 3 = 255

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