Quick Subtraction

This is a special method of subtraction
which many people find quickest (once they get used to it!).

Start Normally

You start the same was as Subtraction by Regrouping (but we aren't going to be doing any regrouping):

write down the larger number first and the smaller number directly below it
making sure to line up the columns!
then do subtractions one column at a time like this (press play button):

But when a column has a smaller number on the top, do this:

1. Reverse the subtraction (to 5 - 2 = 3)

2. Find what would make it to 10 (3 + 7 = 10), write that as part of your answer

3. Add 1 to the digit on the left (of the number you are subtracting).

And this is how to do it:

With a bit of experience the "what adds to 10" becomes automatic. 1→9, 2→8, 3→7, 4→6, 5→5, etc, and the rest is easy.

Here is an example where we need to do it three times: