Breaking down numbers

Here are two different examples where breaking down numbers can help you add or subtract in your head.

Example 1

Try adding 40 + 67.

40 + 67 is the same as...
40 + 60 + 7 which is...
100 + 7 which equals...
107

Example 2

Find the difference between 38 and 63.

Count on from 38 to 40 and keep that 2 in your head.
Now count on from 40 to 60, which is 20.
Finally count from 60 to 63 which is 3.
Add them together: 2 + 20 + 3 = 25.