Roman Numerals

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

Placing an "I" in front of the "V"; or placing any smaller value in front of any larger value, indicates subtraction. That is, the preceding smaller value is subtracted from the following larger value. So "IV" means 4. The value "IIII" is sometimes used for "4". "IIII" is used mostly on faces of clocks and for other special uses. The standard Roman Numeral for "4" is IV.

Placing a smaller value after a larger one indicates that the smaller value is added to the preceding larger value. Thus, after V comes a series of additions - VI means 6, VII means 7, VIII means 8.