here is my (very lame) attempt^{*} to explain the method by which I (and Nancy) learned to subtract

I’ll use the same sum

34-

17

—-

first, grab (borrow) a 1 from the 10’s column, as you do with the Bess method.

3^{1}4-

1 7

—-

7

Then, in the tens column, instead of crossing out the 3 and making it a 2 (a la Bess) making the sum 2-1, you “pay back” the 1 you borrowed to the bottom row and add it to the number that is there – so, in this case, you would have 3-2

3^{1}4-_{1}1 7

—-

1 7

I hope that makes sense!

^{*}please be warned that I have difficulties explaining most things in a coherent manner!