Banned because I do know how they work, I just don't like that google can do math in them.

Proof I know this:
Spoiler:
I = 1
V = 5
X = 10
L = 50
C = 100
M = 1000

If they are the same numeral you add them, if they are different and the smaller numeral is before the larger one, you subtract the smaller one from the larger one and if the larger one is before the smaller one you add them.