Roman numerals refuse to retire: they number movie sequels, Super Bowls, clock faces, book chapters, and monarchs. This converter turns any number from 1 to 3999 into its correct Roman form, subtractive notation included.
工作原理
The converter walks down the value table — M, CM, D, CD, C, XC, L, XL, X, IX, V, IV, I — subtracting each value as many times as it fits and appending the matching symbols, which guarantees the canonical form.
公式
Subtractive pairs handle 4s and 9s: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900. A smaller symbol before a larger one subtracts; after it, adds.
计算示例
2026 = 1000 + 1000 + 10 + 10 + 5 + 1 → MMXXVI. And 1994 showcases the subtractive rules fully: M + CM + XC + IV = MCMXCIV.
常见问题
Why does the converter stop at 3999?
Standard notation has no symbol beyond M, and convention caps repetition at three (MMM = 3000). Larger numbers historically used a bar over symbols to multiply by 1000 — beyond everyday notation.
Why do some clocks show IIII instead of IV?
Watchmaking tradition: IIII balances the VIII opposite it on the dial visually. Both forms have historical precedent, but IV is the standard subtractive form everywhere else.
Is there a Roman numeral for zero?
No — the system predates the concept of zero as a numeral. Medieval scribes sometimes wrote 'nulla' (nothing), but classical notation simply has no symbol for it.