Roman Numerals are A system of dating which is found on most books before 1800 and a great many after 1800. Each numeral has to be added mentally to arrive at the total. Here is the formula for the Roman Numeral numbering system.
xxxi = 31
xxxvi = 36
mcccclxxxiv = 1484
mdxxxxv = 1545
(the x before the l has to be subtracted)
mdcclxxx = 1780
Another way to explain this is as follows: A numeral is a symbol used to represent a number. Each letter used in Roman numerals stands for a different number. A row of letters means that they 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, you must subtract instead of adding. For example, IV= 4 (i.e., one subtracted from five). These rules will be handy in writing Roman numerals. Just convert one digit at a time. Here is an exercise to try: convert 963 to Roman numerals. 963 = 900 + 60 + 3 = CM + LX + III.
There are a few rules in converting Roman numerals to Arabic numbers. They are:
Writing VL for 45 is not allowed: write XLV instead.
This means that you can only subtract I from V or X, and X from L or C.