以下のガイドはまだ日本語に翻訳されていないため、英語で表示しています。計算機自体はすべて日本語に対応しています。
この計算機の使い方
- Choose the direction.
- Enter a whole number between 1 and 3,999, or a Roman numeral such as MCMXCIV.
- Non-standard forms such as IIII or VX are rejected so results stay correct.
計算式
Roman numerals add symbol values from largest to smallest, except where a smaller symbol before a larger one is subtracted. Only I, X and C are used subtractively (IV, IX, XL, XC, CD, CM).
I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000
IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900
Examples
- 2026 = MM + XX + VI = MMXXVI.
- MCMXCIV = M (1000) + CM (900) + XC (90) + IV (4) = 1994.
よくある質問
Why does it stop at 3,999?
Standard notation has no symbol above M, so 4,000 would need MMMM. Larger numbers historically used a bar over a numeral (vinculum) to multiply by 1,000, which isn't standardized.
Is there a Roman numeral for zero?
No. Romans had no symbol for zero; medieval scholars sometimes wrote N (nulla).
Why do some clocks show IIII instead of IV?
It's a long-standing clock-face tradition for visual balance, but IV is the standard form.