For those who are unfamiliar with Roman Numerals, here is a quick summary:
Each letter used in Roman numerals stands for a different number:
Roman Numeral Number
--------------------------
I 1
V 5
X 10
L 50
C 100
D 500
M 1000
A string of letters means that their values should be added together. For example, XXX = 10 + 10 + 10 = 30, and LXI = 50 + 10 + 1 = 61. If a smaller value is placed before a larger one,
we subtract instead of adding. For instance, IV = 5 − 1 = 4 and XC = 100 − 10 = 90.
- Except for M, do not add more than three of the same letters together.
- Subtract only powers of ten, such as I, X, or C. Writing VL for 45 is not allowed: write XLV instead.
- Subtract only a single letter from a single numeral. Write VIII for 8, not IIX; 19 is XIX, not IXX.
- Don't subtract a letter from another letter more than ten times greater. This means that you can only subtract I from V or X, and X from L or C, so MIM is illegal.
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