What Roman numerals represented numbers using letters of the American alphabet?

Answer 1

1 = I

5 = V

10 = X

50 = L

100 = C

500 = D

1,000 = M

For example, 1776 is MDCCLXXVI

However, you are not allowed to have more than four of the same symbol in a row (except for on some clocks with IIII). But if a smaller symbol is in front of a larger symbol, than it is subtracted.

IV = 4

IX = 9 (I can only be subtracted from V and X)

XL = 40

XC = 90 (X can only be subtracted from L and C)

CD = 400

CM = 900 (C can only be subtracted from D and M)

So 1999 is M CM XC IX. Some people write MIM instead of MCMXCIX. This is incorrect because I can't be subtracted from M.