14-billion-years-later:

Just a list of cool little mathematical tricks and other cool things I wanted to make.

Every number divisible by three (to give whole numbers) has a digit sum that is a multiple of 3.
Eg. 186/3=62 (1+8+6=15, 15/3=5 and 1+5=6, 6/3=2)

For dividing by four the last…