You're right - I still use number-sense tricks for fast multiplication :) For Calculator, I wrote https://git.io/ti84rpn https://git.io/ti84rpn so that I could

You're right - I still use number-sense tricks for fast multiplication :) For Calculator, I wrote https://git.io/ti84rpn https://git.io/ti84rpn so that I could use the fast parenthesis-less Reverse Polish Notation without having to adapt to a whole new calculator keyboard.