Add and Subtract Numbers Mentally

In this activity, we will be adding and subtracting mentally.

Sometimes it is quicker to use little number tricks.

Example 1

64 + 46 = ?

Split the numbers into tens and ones first:

60 + 40 = 100

4 + 6 = 10

Add the two totals together: 100 + 10 = 110

So, 64 + 46 = 110

Example 2

26 - 17 = ?

Make the number we're subtracting an easier one to work with - here, we round it up to 20 by adding 3 to it.

26 - 20 = 6

This means that we have subtracted 3 more than we needed to!

So add on the 3 extra that we deducted:

6 + 3 = 9

So, 26 - 17 = 9

There are many other tricks we can use to help with these calculations, so feel free to use any of your own that help you to solve the problems.

Let's give it a go!