My primaryschool maths teacher taught us roman numerals and one of the tasks we got was to write out the current year in roman numerals.
I came up with MCMXCVIII ... to which he smugly replied that it's wrong and the romans were a lot more clever and it's just IIMM (take 2 off 2000).
Years later I learned that he was quite wrong about that and my answer is in fact the only correct one.