The Complete Guide to Roman Numerals
Roman numerals have been used for over 2,500 years, originating in ancient Rome. While we primarily use Arabic numerals (1, 2, 3, etc.) today, Roman numerals still appear in various places like clock faces, book chapters, movie credits, and more. In this guide, we'll teach you how to read, write, and convert Roman numerals.
Roman Numeral Basics
Roman numerals use combinations of letters from the Latin alphabet to represent numbers. Here are the basic symbols and their values:
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1,000 |
How to Read Roman Numerals
Roman numerals are read from left to right. When a smaller number appears before a larger number, you subtract the smaller one (subtractive notation). When a smaller number appears after or equal to the larger one, you add them (additive notation).
Examples:
- VI = 5 + 1 = 6
- IV = 5 - 1 = 4
- IX = 10 - 1 = 9
- XL = 50 - 10 = 40
- XC = 100 - 10 = 90
- CD = 500 - 100 = 400
- CM = 1000 - 100 = 900
Converting Numbers to Roman Numerals
To convert a number to Roman numerals, break it down into thousands, hundreds, tens, and ones, then convert each part separately.
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Common Uses of Roman Numerals Today
- Clock faces (e.g., I, II, III, IV, V, VI, etc.)
- Book volume and chapter numbers
- Movie and TV show copyright years
- Numbering of Super Bowls and other major sporting events
- Monarch and pope names (e.g., Queen Elizabeth II, Pope John Paul II)
- Building construction years on cornerstones
Roman Numerals in Modern Times
While Arabic numerals (0-9) are used for most numerical purposes today, Roman numerals maintain their place in various formal and decorative contexts. They're particularly common in:
- Analog clock and watch faces
- Movie and TV show production years
- Numbering of book volumes, chapters, or sections
- Numbering of annual events (e.g., Super Bowl LVII)
- Page numbering of prefaces and introductions in books
Pro Tip
When writing Roman numerals, remember these rules:
- Never repeat a symbol more than three times in a row (e.g., use IV instead of IIII for 4)
- Only I, X, C, and M can be repeated
- Only one smaller number can be placed before a larger number for subtraction (e.g., IX for 9, but IIX is invalid)
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