Just seven letters and two simple rules: add or subtract. Learn to read and write any Roman numeral up to 3,999, and see where they still appear on clocks, books and sports.
Roman numerals do not use place value the way our everyday numbers do. There is no ones column or tens column. Instead, they work through just seven symbols and two clean rules for combining them. Once those two rules click, any Roman numeral becomes readable, and you can write any number up to 3,999 with confidence. This guide also shows you where Roman numerals are still used today, and why they were replaced for arithmetic.
Roman numerals are the number-writing system used in ancient Rome, built from combinations of just seven letters. Unlike the numbers we use every day, which rely on place value (a digit’s position changes its worth), Roman numerals work by combining symbols according to a few fixed rules.
The system is about 2,000 years old, but it never fully disappeared. It still appears on clock faces, in the credits of films and books, for numbering kings, queens and popes, in the outlines of documents and in numbering major events such as the Super Bowl.
Every Roman numeral, no matter how large, is built from just these seven symbols.
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1,000 |
There is a neat pattern in these values. Going up the list, the value is multiplied by 5, then by 2, then by 5, then by 2 again. That is why the symbols come in a repeating “1, 5, 10” rhythm: I, V, X, then X, L, C, then C, D, M.
When a smaller (or equal) symbol comes after a larger one, add its value.
VI = V (5) + I (1) = 6. XV = X (10) + V (5) = 15. LXVII = L (50) + X (10) + V (5) + I (1) + I (1) = 67.
When a smaller symbol comes before a larger one, subtract the smaller value from the larger one instead of adding it. This is what lets Roman numerals avoid writing the same symbol four times in a row.
IV = V (5) − I (1) = 4. IX = X (10) − I (1) = 9. XL = L (50) − X (10) = 40. CM = M (1,000) − C (100) = 900.
Adding I four times in a row looks like a reasonable way to build 4, but it breaks the standard repetition limit.
The fix: the standard modern form of 4 is IV, using the subtraction rule. IIII does still appear on many clock faces (more on that below), but in standard written use, IV is correct.
A symbol can be repeated to add its value, but only up to three times in a row, and only for the symbols I, X, C and M. The symbols V, L and D are never repeated, ever.
| Can Repeat (up to 3 times) | Never Repeats |
|---|---|
| I, X, C, M | V, L, D |
III = 3 (three I’s, allowed). XXX = 30 (three X’s, allowed). But 4 is never written as IIII in standard form, and 10 is never written as VV. Instead, the subtraction rule or a bigger symbol takes over.
Subtraction cannot be used freely between any two symbols. A smaller symbol may only subtract from the next one or two symbols above it, never further. Only I, X and C can be used to subtract, and only one smaller symbol may be placed in front.
| Smaller Symbol | May Precede (Subtract From) | Gives |
|---|---|---|
| I | V or X only | IV = 4, IX = 9 |
| X | L or C only | XL = 40, XC = 90 |
| C | D or M only | CD = 400, CM = 900 |
| V, L, D | Never used to subtract | VX, LC and DM are invalid |
This looks tempting (“one before a hundred”), but I is only allowed to subtract from V or X, never from C.
The fix: 99 must be built in stages: XC (90) + IX (9) = XCIX. Each subtraction pair can only skip one size level, never jump straight from I to C.
Putting two small symbols in front of a larger one to “subtract 2” seems logical, but only one symbol may be subtracted at a time.
The fix: 18 = 10 + 5 + 3 = X + V + III = XVIII. Use addition here. Subtraction is kept for the special cases 4, 9, 40, 90, 400 and 900.
Here is a method that never fails. Split the number into thousands, hundreds, tens and ones (ordinary place value), then write each part using this table, and join the pieces from left to right.
| Digit | Ones | Tens | Hundreds | Thousands |
|---|---|---|---|---|
| 1 | I | X | C | M |
| 2 | II | XX | CC | MM |
| 3 | III | XXX | CCC | MMM |
| 4 | IV | XL | CD | |
| 5 | V | L | D | |
| 6 | VI | LX | DC | |
| 7 | VII | LXX | DCC | |
| 8 | VIII | LXXX | DCCC | |
| 9 | IX | XC | CM |
1994 = 1,000 + 900 + 90 + 4. From the table: M, CM, XC, IV. Join them: MCMXCIV.
2026 = 2,000 + 20 + 6 = MM + XX + VI = MMXXVI. A zero in a place (here the hundreds) is simply skipped.
444 = 400 + 40 + 4 = CD + XL + IV = CDXLIV.
To read a numeral, move from left to right. Compare each symbol with the one after it. If the next symbol is bigger, subtract the current symbol. Otherwise, add it.
M (1,000) is followed by C, which is smaller, so add: +1,000. C (100) is followed by D (500), which is bigger, so subtract: −100. D (500) is followed by X, which is smaller, so add: +500. X (10) is followed by C (100), which is bigger, so subtract: −10. C (100) is followed by I, so add: +100. I (1) is followed by I, so add: +1. The last I is added: +1.
Total: 1,000 − 100 + 500 − 10 + 100 + 1 + 1 = 1,492. Grouped as pieces: M + CD + XC + II = 1,000 + 400 + 90 + 2 = 1,492. ✓
XL = 40 and IX = 9, so XLIX = 40 + 9 = 49. Not “IL”, because I cannot subtract from L.
Tap any Roman numeral below to see its value and exactly how it breaks down, piece by piece.
Tap a Roman numeral above to see its breakdown.
Because Roman numerals have no place value, adding and especially multiplying them directly is awkward. The easiest way is to convert to ordinary numbers, calculate, and convert back.
(a) XIV + XXVII: 14 + 27 = 41 = XLI.
(b) CCLV − LXIII: 255 − 63 = 192 = CXCII.
(c) XXIV × XVII: 24 × 17 = 408 = CDVIII. Try doing that without converting! Long multiplication on Roman numerals is so hard that it is one reason the Hindu-Arabic place-value system, with its columns, eventually replaced them for calculation. Roman people did calculate, but they used counting boards and an abacus rather than writing sums.
Standard Roman numerals have no symbol for zero. The Romans did not treat zero as a number the way modern mathematics does. That idea developed in India and spread from there, as covered in our Number Systems article. (A few scholars in the early Middle Ages did write the Latin word nulla, meaning “none”, in tables, but this was a word, not a numeral.)
Since I, X, C and M can repeat, it is easy to assume the rule applies to every symbol.
The fix: only I, X, C and M ever repeat, and never more than three times. V, L and D each appear at most once in any numeral. If you ever need “two fives”, you already have a ten (X), so V is never doubled.
Super Bowl championships are numbered using Roman numerals. Super Bowl LVIII (58) took place in 2024. Movie sequels use them (Rocky IV), as do monarchs (Queen Elizabeth II) and the copyright years in old film credits. You will also see them on clock faces, on the cornerstones of buildings, for chapters and prefaces of books, and for the sections of a formal outline.
Many clock faces show 4 o’clock as IIII rather than IV, breaking the standard rule on purpose. Nobody knows for certain why, but one popular theory is that IIII balances visually with VIII on the opposite side of the clock face.
Without extending the notation, the largest standard Roman numeral is 3,999 (MMMCMXCIX), since M can only repeat three times. To write bigger numbers, the Romans put a bar over a numeral to multiply it by 1,000, so a bar over V means 5,000. The longest numeral below 4,000 is 3,888, which is MMMDCCCLXXXVIII.
Tap the correct answer for each question.
1. 38 = 30 + 8 = XXX + VIII = XXXVIII.
2. CD = 400, XL = 40, IV = 4, so CDXLIV = 444.
3. No. V can never be used to subtract. The number 5 is simply V.
1. 1,947 = 1,000 + 900 + 40 + 7 = M + CM + XL + VII = MCMXLVII.
2. M (1,000) + CD (400) + XC (90) + II (2) = 1,492.
3. XIV = 14 and XXVII = 27. 14 + 27 = 41 = XLI.
4. I may only be placed before V or X, so IC is invalid. 99 = 90 + 9 = XC + IX = XCIX.
Learners often memorise the symbols but struggle to write numbers. The place-value table in this guide fixes that, because it connects Roman numerals to the place value they already know. Let students find real examples: clock faces, book prefaces, film credits and building dates. Ask them to write today’s year, their age and their house number. Games such as matching cards or a “Roman numeral treasure hunt” keep practice light. Point out that these numerals show how much easier our own system is for calculation, which links to Place Value & Face Value.
10 questions. Select an answer for each, then submit to see your score instantly.