Roman Numerals Converter
Convert between Roman numerals and decimal numbers.
I, V, X, L, C, D, M
1 - 3999
Basic Symbols
Subtractive Notation
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What are Roman Numerals?
Roman numerals are a numeral system originating from ancient Rome. They use combinations of letters from the Latin alphabet to represent numbers.
Roman numerals are still used today for clock faces, book chapters, movie sequels, Super Bowl numbers, and formal documents.
The Seven Basic Symbols
| Symbol | Value | Origin |
|---|---|---|
| I | 1 | One finger |
| V | 5 | Hand (5 fingers) |
| X | 10 | Two hands crossed |
| L | 50 | Half of C |
| C | 100 | "Centum" (Latin for 100) |
| D | 500 | Half of M |
| M | 1000 | "Mille" (Latin for 1000) |
Rules for Writing Roman Numerals
1. Addition Rule When a smaller numeral follows a larger one, add them:
- VI = 5 + 1 = 6
- XI = 10 + 1 = 11
- LX = 50 + 10 = 60
2. Subtraction Rule When a smaller numeral precedes a larger one, subtract:
- IV = 5 - 1 = 4
- IX = 10 - 1 = 9
- XL = 50 - 10 = 40
- XC = 100 - 10 = 90
- CD = 500 - 100 = 400
- CM = 1000 - 100 = 900
3. Repetition Rule A symbol can be repeated up to 3 times:
- III = 3 ✓
- XXX = 30 ✓
- IIII = 4 ✗ (should be IV)
Examples
| Year | Roman Numeral | Breakdown |
|---|---|---|
| 2024 | MMXXIV | M+M+X+X+IV = 1000+1000+10+10+4 |
| 1999 | MCMXCIX | M+CM+XC+IX = 1000+900+90+9 |
| 2000 | MM | M+M = 1000+1000 |
| 1776 | MDCCLXXVI | M+D+C+C+L+X+X+V+I |
Limitations
- Maximum value: 3999 (MMMCMXCIX)
- No zero: Romans didn't have a concept of zero
- No fractions: Roman numerals only represent whole numbers
- No negative numbers: Cannot represent negative values
Modern Uses
- Clocks: Traditional clock faces often use Roman numerals
- Outlines: I, II, III for major sections
- Monarchs: King Henry VIII, Queen Elizabeth II
- Movies: Rocky IV, Star Wars Episode IX
- Events: Super Bowl LVIII, Olympics XXX
- Buildings: Cornerstones with construction year