What Are the Roman Numerals?

Updated on March 23, 2013

By Joan Whetzel

Roman Numerals form a unique numbering system that has been around for centuries. Like other numbering systems (i.e. the Mayan numbers) Roman numerals are no longer used for regular counting purposes, having been replaced by Arabic numbers. They are still applicable today for a few specific uses, however. A bit of mathematical logic will need to be applied when using Roman numerals in order to Use them correctly.

Roman Numeral Usage

When the Roman Numeral system was invented is qnot ite clear, though it is believed to have begun prior to the middle ages. Roman numerals are still used today in a number of applications, such as:

1. to create outlines, usingn Roman Numerals for topics (I, II, III, IV, V) , capitol letters (A,B,C) for the main points and lower case Roman Numerals and letters (i, ii, iii, iv, v; a,b,c) for finer details and supporting evidence.

2. to number clocks and watch faces.

3. to number the pages in the prefaces and forwards of books.

4. to number book chapters.

5. to number movies and events that appear in a series or in a set of sequels (i.e. Super Bowl XV or Men In Black III).

6. to follow the names of monarchs (Henry VIII) and Popes (Benedict XVI).

7. in scientific circumstances, to indicate intensity or to clarify specific features.

8. to indicate the date of publication in books.

9. to indicate the year a film was first released to theaters.

What Are the Roman Numerals?

Roman numerals use letters to symbolize 7 basic numbers as listed in the table below. Numbers and numerals are not exactly the same thing. Numbers are the things (1,2,3…) that we use in math and for counting. Numerals, on the other hand represent the numbers without actually being a number. In Roman numerals, the letter "I" represents the number 1, "V" stands for 5, X signifies 10, L is used to symbolize 50, C is used to denote 100, and M is used as an indicator for 1,000.

Each of these letters can be used in combination with any of the other letters to symbolize the numbers in between.

Roman Numerals - Doing The Math

The table below illustrates the general principles for using Roman numerals in combination. There are a few rules for placing the numerals in the correct order in order to obtain the correct number.

The rules are pretty simple and straight forward:

· When a smaller numeral comes after a larger numeral, the numbers they represent are added together. Example: VIII = V + III, which translates to Arabic numbers as 8 = 5 + 3; LXXX L + X + X + X, which is the same as 80 = 50 + 10 + 10 + 10.

· When a smaller numeral comes before a larger numeral, the numbers are subtracted. Example: IX = X - I or 9 = 10 - 1; CM = M - C which is the same as 900 = 1 ,000 - 100; XXIV = XX + (V - I), or 24 = 20 + (5 - 1) = 20 + 4 in Arabic numbers.

· Only single numerals can be subtracted from a lager numeral. Example: 8 is VIII not IIX, meaning 2 cannot be subtracted from 10 to get, 3 Is have to be added to the V.

· Only subtraction of powers of ten (I, X, C) is allowed. Example: The number 45 has to be written as XLV = (L - X) + V [(50 - 10) +5], it can't be written as VL = L - V [which equates to 50 - 5 in Arabic numbers].

· Don't subtract a numeral from another numeral that's more than 10 times larger Example: Only I and V can be subtracted from X, only X can be subtracted from L or C, and only C can be subtracted from D or M.

Once the numerals start getting really large, the rules change a bit to accommodate the larger amounts. The number 1,000 is represented by the Roman numeral "M" which is easier to use than "1,000" but if you string enough of those Ms together it gets a bit unwieldy (7,000 = MMMMMMM). So, the Romans tweaked the rules to make the numerals easier to deal with.

· Larger numerals (strings of 1,000s or Ms) are changed to a lower case numeral and a line is drawn over them, so, for instance, the number 7,000, instead of reading "MMMMMMM", would look like this:

· A single numeral or numeral set can be increased in value 1,000 times simply by placing a bar over the numeral. Example: XV = 15, but 15,000 is represented by:

17

2

2

114

31

8