Roman Numerals

Roman numerals originated in ancient Rome and remained the standard way of writing numbers throughout Europe well into the Middle Ages. They use combinations of letters from the Latin alphabet.

Symbols

I = 1 V = 5 X = 10 L = 50 C = 100 D = 500 M = 1000

How it works

Roman numerals are primarily additive: values are summed left to right. However, a smaller value placed before a larger one indicates subtraction:

IV = 5 − 1 = 4 IX = 10 − 1 = 9
XL = 50 − 10 = 40 XC = 100 − 10 = 90 CM = 1000 − 100 = 900

Examples

XLII = 40 + 2 = 42

MCMXCIV = 1000 + 900 + 90 + 4 = 1994

Rules

Roman numerals can represent numbers from 1 to 3999. I, X, C, and M can be repeated up to three times. V, L, and D are never repeated. The subtractive combinations IV, IX, XL, XC, CM, and CD are the only allowed subtractions.