What is 645 in Roman Numerals?

Answer 1

In Roman numerals, M = 1000, D = 500, C = 100, L = 50, X = 10, V = 5, and I = 1. A single Roman numeral of lesser value placed before a Roman numeral of higher value means to subtract the lesser one, so CM = 900, CD = 400, XC = 90, XL = 40, IX = 9, and IV = 4, but the lesser one should be no more than one power of 10 less, meaning you do not write IC to mean 99.

So, 600 = DC, 40 = XL, and 5 = V, which combined will give you 645 = DCXLV. DCXXXXV or VDCL but not as DCXLV