How to read Roman Numerals?

Answer 1

Work from the left, converting each symbol into it equivalent value. The values should be in descending order, but where a smaller value precedes a larger value (known as a subtractive pair), the smaller value is negated. You cannot have two negative values in succession. Once you've converted each symbol to a number, you simply add them together (subtracting the negatives) to get the actual number.

Thus MCMLXXXIV can be written as 1000 - 100 + 1000 + 50 + 10 + 10 + 10 - 1 + 5, which comes to 1984. Thus MCMLXXXIV is the Roman numeral for 1984.

There are only 7 symbols to consider: I, V, X, L, C, D and M, representing values 1, 5, 10, 50, 100, 500, 1000 respectively.

The value 4 can be represented as IIII or as IV. Similarly with 9, as VIIII or IX. However no other symbol should repeat more than 3 times in succession. Thus 40 is XL, 90 is XC, 400 is CD and 900 is CM. No other subtractive pairs are permitted although you may encounter weird combinations such as MIM (1999) and IIXX (18), which are considered to be invalid under the accepted convention. The correct notation for these numbers are MCMXCIX (or MCMXCVIIII) and XVIII, respectively.