## Roman numerals

This numeric system originated in ancient Rome. Numbers in this system are represented by combinations of letters from the Latin alphabet.

They are based on the following seven symbols, each with a fixed integer value:

Symbol | Value |

I | 1 |

V | 5 |

X | 10 |

L | 50 |

C | 100 |

D | 500 |

M | 1000 |

Basic numbers look like this:

1 - I

2 - II

3 - III

4 - IV

5 - V

6 - VI

7 - VII

8 - VIII

9 - IX

10 - X

15 - XV

20 - XX

40 - XL

50 - L

60 - LX

80 - LXXX

100 - C

200 - CC

300 - CCC

400 - CD

500 - D

700 - DCC

900 - CM

**How to form a number:**

A symbol placed after another of equal or greater value adds its value:

II=I+I=1+1=2

III=I+I+I=1+1+1=3

LXXX=L+X+X+X=50+10+10+10=80

MDCXXI=1000+500+100+10+10+1=1621

A symbol placed before one of greater value subtracts its value:

IV = V − I = 5 − 1 = 4

XC = C − X = 100 − 10 =90

No digit is repeated in succession more than thrice. The digits I, X and C can be repeated up to three times in succession to form the numbers. V, L and D are not repeated at all.

**How to form a Roman numeral:**

To convert a number to a Roman numeral write the numbers in expanded form and then replace the terms with correct symbols:

1511=1000+500+10+1=M+D+X+I=MDXI

969=900+60+9=CM+LX+IX=CMLXIX