Reminders to help you add and subtract

Here are three reminders to help you with mental addition and subtraction.

A reminder about place value

Have a look at the number 623.

• 6 is the hundreds digit.
• 2 is the tens digit.
• 3 is the units digit.

A reminder about adding

Have a look at these sums.

Here you can see that the same numbers added together in a different order will give the same answer.

Addition and subtraction are opposites.

You can check the answer to a subtraction sum by turning the numbers around and adding them up. Have a look below.

Here you've done the sum 10 - 25 and got the answer 15.
To check the answer, turn the sum around to 15 + 10 and see if you get 25.