I've received, both here and at kitchentablemath, a number of interesting non-stacking strategies for computing 825 - 267 that I had never thought of before. This made me wonder about just how far one can get without stacking. What happens when we add a few more digits?
For example, how about--using numbers randomly generated by my software program--885.66 minus 746.85?
My new question: Is there a way to subtract 746.85 from 885.66 that
1. Isn't massively facilitated by stacking one number on top of the other;If so, please share it here!
2. Only uses methods that grade school children can discover on their own;
3. Doesn't place excessive demands on short-term memory?