| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1,000 |
| # | Roman | # | Roman | # | Roman |
|---|---|---|---|---|---|
| 1 | I | 11 | XI | 60 | LX |
| 2 | II | 12 | XII | 70 | LXX |
| 3 | III | 13 | XIII | 80 | LXXX |
| 4 | IV | 14 | XIV | 90 | XC |
| 5 | V | 15 | XV | 100 | C |
| 6 | VI | 19 | XIX | 400 | CD |
| 7 | VII | 20 | XX | 500 | D |
| 8 | VIII | 30 | XXX | 900 | CM |
| 9 | IX | 40 | XL | 1000 | M |
| 10 | X | 50 | L | 2026 | MMXXVI |
Split the number by place value and convert each part, then join them. 1984 breaks into 1000 + 900 + 80 + 4, giving M + CM + LXXX + IV = MCMLXXXIV. 2026 breaks into 2000 + 20 + 6, giving MM + XX + VI = MMXXVI.
Recent and upcoming years follow the same pattern: 2020 is MMXX, 2024 is MMXXIV, 2025 is MMXXV, 2030 is MMXXX, and 2050 is ML in shorthand — properly MML.
Only six subtractive pairs are valid: IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900). A smaller symbol may be subtracted only from the next one or two steps up, which is why 99 is written XCIX rather than IC. I, X, C and M may repeat up to three times; V, L and D never repeat.
The standard system stops at 3,999 — MMMCMXCIX. Larger values historically used a bar over the numeral to multiply it by a thousand, a notation rarely seen today.
Roman numerals are purely additive, so there is no place value to hold empty and therefore no need for a symbol meaning nothing. That is fine for recording quantities and hopeless for calculating with them. Multiplying MCMXLVII by XXIII is not a task anyone attempts twice.
Roman merchants did not, in fact, try. They worked on a counting board — an abacus with grooves for each place value — and used numerals only to record the result. Positional notation with a zero arrived in Europe through Arabic mathematics much later, and it displaced Roman numerals for arithmetic precisely because it made written calculation possible.
They survive wherever formality, tradition, or category-marking matters rather than quantity. Monarchs and popes are numbered this way, as are Olympic Games and Super Bowls. Film and television productions still place copyright years in Roman numerals in the closing credits, a convention that began partly because it made the date less immediately obvious to audiences.
Books use them for front matter pagination, keeping the preface separate from the numbered body. Formal outlines nest them alongside letters and Arabic numerals to signal hierarchy. Chemistry writes oxidation states this way — iron(III) chloride — and music theory uses them for chord degrees, where a numeral marks a function rather than a count.
And clock faces, of course, where IIII rather than IV is standard on the vast majority of dials. No definitive explanation exists; the most common account is visual balance against the VIII directly opposite.