Roman Numbers

Introduction to Roman Numbers

Roman numerals are a system of numerical notation used in ancient Rome and still in limited use today. In this system, different letters represent different values, and the numbers are created by adding or subtracting these values.

Symbols and their values:

The Roman numerals use seven different letters that represent specific values as shown below:

Roman Number Rules

Roman Number Rules

1. Roman numerals are written using only seven letters: I, V, X, L, C, D, and M. Each letter represents a specific value: I represents the number 1 V represents the number 5 X represents the number 10 L represents the number 50 C represents the number 100 D represents the number 500 M represents the number 1,000

 2. Roman numerals are read from left to right, and the values of the letters are added together to determine the total value of the number.

 3. When a letter is written before another letter of greater value, its value is subtracted from the greater letter.

 For example:

 IV represents the number  4 (I before V, subtract 1 from 5)

 IX represents the number 9 (I before X, subtract 1 from 10)

XL represents the number 40 (X before L, subtract 10 from 50)

XC represents the number 90 (X before C, subtract 10 from 100)

 CM represents the number 900 (C before M, subtract 100 from 1,000)

 4. Roman numerals are written using the fewest possible number of letters.

For example, the number 4 is written as IV, not IIII.

 5. There is no symbol for zero in Roman numerals.

6. Roman numerals can be used to represent years, book chapters, movie sequels, and other types of numerical information.

Roman Numbers

Writing Roman Numerals

Example 1 : Write the following numbers in roman numerals: (a) 1287 (b) 699 (c) 789

         (a) 1287

 1287 = 1000 + 200 + 80 + 7 = MCCLXXXVII

(b)699

 699 = 600 + (100 - 10) + (10 - 1) = DCXCIX

(c)789

789 = 700 + 80 + (10 - 1) = DCCLXXXIX

Example 1 : Write the following roman numerals in Hindu-arabic numbers:

 (a) DCCLVI        (b) MXVIII         (c) MDCCCLXXXVIII

       (a) DCCLVI

          DCCLVI = 500 + 200 + 50 + 5 + 1 = 756

         (b) MXVIII

           MXVIII = 1000 + 10 + 5 + 3 = 1018

        (c)MDCCCLXXXVIII

MDCCCLXXXVIII = 1000 + 500 + 300 + 50 + 30 + 8 = 1888