2.1.6 Roman Numerals
The following are the roman numerals commonly tested on the exam:
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1000 |
Knowing the above table and also the fact that you arrange the numerals in order from greatest to least (M → I) with the exception of one rule: you can’t put four of the same numerals consecutively.
For example, to express 42 in roman numerals it would not be 42 = XXXXII, it would be 42 = XLII. To circumvent the problem of putting four of the same numerals consecutively, you use a method of “subtraction.” Anytime a numeral of lesser value is placed in front of a numeral of greater value, you subtract from the larger numeral the small numeral. So in our case 40 is represented by XL = 50 − 10 = 40.
When converting numbers, it is best to think of the number as a sum of ones, tens, hundreds, etc… units). A good example of what I mean is to express 199 in roman numerals. The way you want to look at it is 199 = 100 + 90 + 9 then express each one as a roman numeral. So 100 = C, 90 = XC, and 9 = IX, so 199 = CXCIX.