Number System Part 1 – Roman Numerals

Before the widespread usage of the Arabic number system, there were other ways to represent numbers. Let’s look at Roman numerals.

The Roman number system was widespread throughout Europe from the time of the Roman Empire until the 14th century due to the introduction of the Arabic number system.

\mathrm{I} = 1      \mathrm{V} = 5     \mathrm{X} = 10      \mathrm{L} = 50      \mathrm{C} = 100        \mathrm{D} = 500     \mathrm{M} = 1000

To form numbers, these letters are stringed together and added. The number 2 is \mathrm{II}, the number 12 is \mathrm{XII} and 325 is \mathrm{CCCXXV}. The largest letters are on left and the smallest on the right. The numbers 4, 9, 40, 90, 400 and 900 are formed differently; 4 = \mathrm{IV}, 9 = \mathrm{IX}, 40 = \mathrm{XL}, 90 = \mathrm{XC}, 400 = \mathrm{CD} and 900 = \mathrm{CM}. Thus the number 499 is formed as \mathrm{CDXCIX}.

For large numbers a bar is placed on top of the number. A number with a bar on top of it means that it is multiplied by a thousand. For example \overline{ \mathrm{IV}} is 4000.

Fun fact, the Romans had no symbol zero. Also Latin for ten, one hundred, and one thousand are decem, centum, and mille respectively.