Use the formula ALL FROM 9 AND THE LAST FROM 10 to
perform instant subtractions.

For example 1000 - 357 = 643

We simply take each figure in 357 from 9 and the last figure from 10.

So the answer is 1000 - 357 = 643

Using VERTICALLY AND CROSSWISE you do
not need the multiplication tables beyond 5 X 5.

Suppose you need 8 x 7
8 is 2 below 10 and 7 is 3 below 10.
Think of it like this:

The answer is 56.
The diagram below shows how you get it.