subtraction by decomposition

This is a vertical method of subtraction.

The number in the upper line is broken down to help with the calculation.

We can use the following sum as an example.

182 – 26 = 156

We can’t subtract 6 from 2, so we need to change the 8 Tens to 7 Tens and add 10 Units to the original 2 to give 12. After doing this, we can subtract 6 from 12 which gives 6. Then, we subtract 2 from 7 which gives 5.