Modular arithmetic is fun. I'm excercising mental modular arithmetic. For the Doomsday algorithm for computing weekday for an arbitrary date There is some mod

Modular arithmetic is fun. I'm excercising mental modular arithmetic. For the Doomsday algorithm for computing weekday for an arbitrary date There is some modulo 7 arithmetic and find myself routinely thinking about some numbers like 5 or 6 as -2 and -1 reapectively