Roman Numerals

Roman numerals are always a fun thing to deal with. I was fortunate enough to have taught seven classes (in one day) on Roman numerals once. Since they are pretty standard it is no problem for me to read them. However, sometimes the patrons or my assistants are not able to get a handle on what symbol stands for which number. And then there is always the fun that is created when the publisher loses track of where they are and then places whatever one they want (or so it seems) on the issue. Then there are the publishers who insist on using "X" as many times as they want -- disregarding the regular rules and making me have to go "ok, was that X for 10 more or to take away from the next symbol?"