Roman Numerals Explained: Chart, History & Subtractive Rules

Although modern society relies on the Arabic decimal numeral system (0 through 9) for mathematics and commerce, Roman numerals remain prominent in book chapter headings, copyright dates on films, clock dials, and Super Bowl titles.

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The 7 Fundamental Roman Numeral Symbols

The entire classical Roman numeric system is built upon just seven Latin letters:

| Symbol | Arabic Value | Origin Meaning | |---|---|---| | I | 1 | Single finger / tally mark | | V | 5 | Hand with thumb spread outward | | X | 10 | Two crossed hands | | L | 50 | Half of the Etruscan numeral for 100 | | C | 100 | Centum (Latin for 100) | | D | 500 | Half of the Greek letter Phi | | M | 1,000 | Mille (Latin for 1,000) |

Translate Instantly: Convert any number or year with our Roman Numerals Converter.

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The 4 Core Rules of Roman Numerals

1. Additive Rule: When symbols are written in descending order from left to right, their values are added together.
   • Example: XVI = 10 + 5 + 1 = 16.
2. Subtractive Rule: A smaller symbol placed immediately before a larger symbol is subtracted from the larger one:
   • IV = 4 (5 - 1)
   • IX = 9 (10 - 1)
   • XL = 40 (50 - 10)
   • XC = 90 (100 - 10)
   • CD = 400 (500 - 100)
   • CM = 900 (1000 - 100)
3. No Quadruple Repetition: A symbol cannot be repeated more than three consecutive times. For example, 4 is written as IV, never IIII.
4. No Zero Symbol: The Romans had no numeric symbol for zero (0), using the Latin word nulla instead.