Which Roman numeral stands for 500?

D stands for 500 in Roman numerals. The full set runs I for one, V for five, X for ten, L for fifty, C for a hundred, D for five hundred and M for a thousand, and the pattern alternates between ones and fives at each power of ten. C is easy to recall because it matches centum, the Latin for hundred, and M matches mille for thousand. D and L have no such mnemonic in modern words, so they are the two people most often mix up. The system uses subtraction to keep strings short: IV is four rather than IIII, and CM is nine hundred. There is no zero and no place value, which makes arithmetic awkward and is a large part of why Hindu-Arabic numerals displaced them for calculation. Roman numerals survive in clock faces, book chapter numbers, film copyright dates and monarchs' titles, where their formality matters more than their convenience.

The year 1888 needs thirteen characters in Roman numerals, MDCCCLXXXVIII, the longest of any year in the modern era.