# What are Roman Numerals?

### Roman Numerals

Roman Numerals are a special kind of numerical notations that were earlier used by the Romans. It is an additive and subtractive system in which letters are used to denote certain base numbers and arbitrary numbers in the number system and denoted using a different combination of symbols.

### Roman Letters

The roman letters are the English alphabets but not all the alphabets are the roman alphabets. There are 23 roman letters out of 26 English alphabets, in which J, U, and W are not considered as roman. Hence, the roman letters are:
A, B, C, D, E, F, G, H, I, K, L, M, N, O, P, Q, R, S, T, V, X, Y, and Z.
All these letters are used to represent the roman numbers. For example, the year 2019 is written as MMXIX.

We can easily convert any numbers into a roman form and conversely, any roman form into any number. Let us understand with the help of an example, Consider a number, 1984

Convert number into the roman form

Break the number 1984 into 1000, 900, 80, and 4, then perform each conversion

As, 1000 + 900 + 80 + 4 = 1984

• 1000 = M
• 900 = CM
• 80 = LXXX
• 4 = IV

1000 + 900 + 80 + 4 = 1984,

So, 1984 = MCMLXXXIV

The numerals for 4 (IV) and 9 (IX) are written using “subtractive notation”, where the first symbol (I) is subtracted from the larger one (V, or X), thus avoiding the clumsier (IIII, and VIIII). The subtractive notation is also used for 40 (XL) and 90 (XC), as well as 400 (CD) and 900 (CM). These are the only subtractive forms in standard use.

A number containing several decimal digits is built by appending the Roman numeral equivalent for each, from highest to lowest, as in the following examples:

•    39 = XXX + IX = XXXIX.
•   246 = CC + XL + VI = CCXLVI.
•   789 = DCC + LXXX + IX = DCCLXXXIX.
• 2,421 = MM + CD + XX + I = MMCDXXI.

The Roman Numerals that represent the numbers are as follows:

 Number Roman Numeral 1 I 5 V 10 X 50 L 100 C 500 D 1000 M