Chamberlain College of NursingHESI A2HESI Mathematics.

Roman Numerals Roman numerals is the ancient number system used in the Roman Empire. In select situations, they are still used as an alternative to the modern numeral system. Roman numerals are based on the idea of adding, and in special cases, subtracting, to represent each number. The following table provides a list of the most commonly used Roman numerals today and their meaning. Roman Numeral Numerical Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000 Roman numerals are written from left to right, greatest numeral to smallest. As you read them, add together the symbols for the numeric value. Example: Erica is visiting Rome for vacation. She sees an old building with “MCCLIII” written on it. What number is this? Looking at our reference chart, we see the first symbol, M, is 1000. CC is 100+100, L is 50, and III is 1+1+1. Adding this together shows that: 1000 + 100 + 100 + 50 + 1 + 1 + 1 = 1253 as the number on the building. There are a few special cases where instead of adding, we subtract to find the meaning of the Roman numeral. These special cases occur when we want to avoid stringing four instances of a symbol together (like IIII for 4 or VIIII for 9). Instead, we use one of the symbols for a power of ten (I, X, C, M) and place it before a symbol with a greater numeric value. An example of the first time this would occur is for the value of four. This is written as IV, or “5 minus 1.” The next time this occurs is for the number nine, IX, or “10 minus 1.” Forty is denoted by XL, or “50 minus 10,” while ninety is XC, or “100 minus 10.”