ROMAN NUMERAL SYSTEM
The Roman numeral system uses letters as symbols for numbers. But the early Roman system of about 500 BC differed from the system we use today. For example, the ancient Romans wrote 4 as IIII and 9 as VIIII. Today, we use IV for 4, IX for 9, L for 50 and M for 1,000. The numerals VI, XV, and LX illustrate the additive principle. When the first of two symbols stands for a larger number than the second, you add the value of th e first to the second to get the value of the combination. Thus, the Roman numeral VI represents 6, or 5 + 1; XV represents 15 as 10 + 5; and LX represents 50 + 10 = 60.
The numerals IV and IX illustrate the subtractive principle. When the first of two symbols stand for a smaller number than the second, you subtract the value of the first from that of the second to get the value of the combination. Thus, in the Roman numeral IV, you subtract 1 from 5 to get 4.