W.H.A.T. Weekday — Human Arithmetic Trainer

Given any date calculate its weekday, in your head, in seconds. Step-by-step guide, exercises, tests and games. An easy and practical way to learn the Doomsday First algorithm. Includes, among other small tools, the memory game Slow Memories requiring day-of-week calculation to flip a card and the power-users' Explorer to follow algorithm steps. /what-weekday






