For years I used Soulver, a Mac-based calculator app that let you write out calculations and formula, and it would render the calculations on the fly. It was a superb way to think out loud with numbers. One of things I loved is that it showed you the record of eƒach calculation, so you could visually follow your chain of mathematical reasoning — kind of like in the old days, with calculators that typed out each line of figures on a spool of paper. — Read the rest
