Question 42062
The Roman Numerals are an ancient number system used by the early Romans.
I = 1
II = 2
III = 3
IV = 4
V = 5
Note that 4 is represented by placing "I" in front of V. 
This means to subtract 1 from 5 or (5-1=4). This is common in Roman Numerals.
VI = 6
Note that the "I" is placed after the "V". 
This means to add 1 to 5 or (5 + 1 = 6)
VII = 7
VIII = 8
IX = 9 (10-1=9)
X = 10
XI = 11 (10+1=11)
XII = 12, etc., continued the same as the one's.
The twenties, thirties, and forties are represented by X's. 
XX = 20 (10 + 10 = 20)
XXX = 30 (10 + 10 + 10 = 30)
XXXX = 40
The fifty's = L
For example: 55 = LV. 
Example: 40 = XL (50-10 = 40)
The hundred's = C
The Five hundred's = D
The One thousand's = M
(Source: http://education.yahoo.com/reference/dictionary/entry?id=r0294100)
For a more complete listing, rules and definition of Roman Numerals, you may want to search the web under "Roman Numerals". I found a lot of sites.