1942 adding machines: a marvel of non-essential zero elimination!

This 1942 ad for a Comptometer mechanical adding machine celebrates the joy of spending hours every day doing what spreadsheets today accomplish in an eyeblink. I love the feature-list: no glare dials, the elimination of non-essential zeroes, and a marvellous "Keystroke Censor."

Collier's January 17, 1942