when you use //, it basically rounds to the smaller number, if you have 1.3 it becomes 1, if you have 79.8, it becomes 79,
so it always round to the smaller, but what happens when the number is negative, -79.8, the smaller number is -80, and that's
the way to do ceil and floor without using any of the method, number // divisor to get the floor, and -(-number//divisor),
to have the ceil, pretty neat :D

Rounding towards negative infinity. https://python-history.blogspot.com/2010/08/why-pythons-integer-division-floors.html