Quote:
Originally Posted by rad
49 is XLIX, I think.
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You are right, generally, though I had to look it up.
There is no formal set of rules, but over time most people have adopted and observe a few unofficial rules:
1) I, X, C, and M can be repeated only 3 times in succession. They can appear 4 times if separated by a smaller letter. (e.g. XXXIX) V, L, and D can never be repeated.
2) I can be subtracted only from V and X. X can be subtracted only from L and C. C can be subtracted only from D and M. V, L, and D can never be subtracted.
3) Only one smaller letter can be subtracted from a particular larger letter.