Yeah, but the real Romans never did that, they represented four with IIII, it's only us moderns that do IV. Actually, the whole add to the right/subtract from the left thing is largely a recent invention, the ancients didn't really have any pattern to their number making. The numeral M is also modern, the Romans never used it, they used a C, a vertical line, and a backwards C to represent a thousand (which might look a little like an M if you drew it fast). C also wasn't short for centum, either, it was another strange symbol that just looked vaguely like a C so that's how we write it now.
Most of our history was made up [edit: "about"] 50 to 75 years ago, I'd wager to say.