Write 39 in Roman numerals.

XXXIX — Split 39 into 30 + 9. 30 = XXX. 9 = IX, one of the six subtractive pairs. Write the larger part first: XXXIX.

Write XLII as an ordinary number.

42 — XL is a subtractive pair: X before L means 50 − 10 = 40. II = 2. 40 + 2 = 42.

Write 74 in Roman numerals.

LXXIV — Split 74 into 50 + 20 + 4. 50 = L, 20 = XX. 4 = IV, not IIII in written form. LXXIV.

Write XCVI as an ordinary number.

96 — XC is X before C: 100 − 10 = 90. V = 5 and I = 1. 90 + 5 + 1 = 96. Reading XC as 110 by adding is the usual slip here.

Write 449 in Roman numerals.

CDXLIX — Split 449 into 400 + 40 + 9. 400 = CD, 40 = XL, 9 = IX. All three parts are subtractive pairs, one after another. CDXLIX.

Write MCMXCIV as an ordinary number.

1994 — Chunk it: M, CM, XC, IV. M = 1000, CM = 900, XC = 90, IV = 4. 1000 + 900 + 90 + 4 = 1994.

Write 2026 in Roman numerals.

MMXXVI — Split 2026 into 2000 + 20 + 6. 2000 = MM, 20 = XX, 6 = VI. No subtractive pair is needed anywhere in this year. MMXXVI.

Write DCCCLXXXVIII as an ordinary number.

888 — Chunk it: DCCC, LXXX, VIII. DCCC = 500 + 300 = 800. LXXX = 50 + 30 = 80. VIII = 8, so the total is 888. At twelve letters this is the longest numeral for any number below 1,000.

Write the year 1948 in Roman numerals.

MCMXLVIII — Split 1948 into 1000 + 900 + 40 + 8. 1000 = M, 900 = CM, 40 = XL. 8 = VIII. MCMXLVIII.

A clock dial shows IIII where you expected IV. What number is it, and is the dial wrong?

4 — and the dial is not wrong — IIII is four ones added together, so it reads as 4. In written Roman numerals the subtractive form IV is the standard, and school work should use it. Clock and watch dials have used IIII for centuries; it is a separate convention, not an error. Look at a dial with a VIII opposite and the IIII will usually be there.

Explain why 1990 cannot be written MXM, and give the correct numeral.

MCMXC — Subtraction is only allowed with I, X or C placed before one of the next two larger letters. X may go before L and C only, so XM is not a legal pair. Split 1990 properly: 1000 + 900 + 90. 1000 = M, 900 = CM, 90 = XC, giving MCMXC.

Put these in order, smallest first: XLIV, LIV, XLIX, XCI.

XLIV, XLIX, LIV, XCI — XLIV = 40 + 4 = 44. LIV = 50 + 4 = 54. XLIX = 40 + 9 = 49. XCI = 90 + 1 = 91. In order: 44, 49, 54, 91, so XLIV, XLIX, LIV, XCI.

Mathématiques

Roman Numerals Practice Questions, Both Ways to 1,000

Twelve questions converting both ways to 1,000, covering IV, IX, XL, XC, CD and CM, plus years, ordering, and the clock dial that prints IIII rather than IV.

La réponse en bref
Roman numerals use seven letters — I, V, X, L, C, D, M — written largest first and added together, with six subtractive pairs as the only exceptions: IV is 4, IX is 9, XL is 40, XC is 90, CD is 400 and CM is 900. So MCMXCIV reads as 1994.

Les exercices

Exercice 1Base1 points
Write 39 in Roman numerals.
Afficher la correctionMasquer la correction
XXXIX
1. Split 39 into 30 + 9.
2. 30 = XXX.
3. 9 = IX, one of the six subtractive pairs.
4. Write the larger part first: XXXIX.
Exercice 2Base1 points
Write XLII as an ordinary number.
Afficher la correctionMasquer la correction
42
1. XL is a subtractive pair: X before L means 50 − 10 = 40.
2. II = 2.
3. 40 + 2 = 42.
Exercice 3Base1 points
Write 74 in Roman numerals.
Afficher la correctionMasquer la correction
LXXIV
1. Split 74 into 50 + 20 + 4.
2. 50 = L, 20 = XX.
3. 4 = IV, not IIII in written form.
4. LXXIV.
Exercice 4Base1 points
Write XCVI as an ordinary number.
Afficher la correctionMasquer la correction
96
1. XC is X before C: 100 − 10 = 90.
2. V = 5 and I = 1.
3. 90 + 5 + 1 = 96.
4. Reading XC as 110 by adding is the usual slip here.
Exercice 5Standard2 points
Write 449 in Roman numerals.
Afficher la correctionMasquer la correction
CDXLIX
1. Split 449 into 400 + 40 + 9.
2. 400 = CD, 40 = XL, 9 = IX.
3. All three parts are subtractive pairs, one after another.
4. CDXLIX.
Exercice 6Standard2 points
Write MCMXCIV as an ordinary number.
Afficher la correctionMasquer la correction
1994
1. Chunk it: M, CM, XC, IV.
2. M = 1000, CM = 900, XC = 90, IV = 4.
3. 1000 + 900 + 90 + 4 = 1994.
Exercice 7Standard2 points
Write 2026 in Roman numerals.
Afficher la correctionMasquer la correction
MMXXVI
1. Split 2026 into 2000 + 20 + 6.
2. 2000 = MM, 20 = XX, 6 = VI.
3. No subtractive pair is needed anywhere in this year.
4. MMXXVI.
Exercice 8Standard2 points
Write DCCCLXXXVIII as an ordinary number.
Afficher la correctionMasquer la correction
888
1. Chunk it: DCCC, LXXX, VIII.
2. DCCC = 500 + 300 = 800.
3. LXXX = 50 + 30 = 80.
4. VIII = 8, so the total is 888.
5. At twelve letters this is the longest numeral for any number below 1,000.
Exercice 9Approfondi2 points
Write the year 1948 in Roman numerals.
Afficher la correctionMasquer la correction
MCMXLVIII
1. Split 1948 into 1000 + 900 + 40 + 8.
2. 1000 = M, 900 = CM, 40 = XL.
3. 8 = VIII.
4. MCMXLVIII.
Exercice 10Approfondi
A clock dial shows IIII where you expected IV. What number is it, and is the dial wrong?
Afficher la correctionMasquer la correction
4 — and the dial is not wrong
1. IIII is four ones added together, so it reads as 4.
2. In written Roman numerals the subtractive form IV is the standard, and school work should use it.
3. Clock and watch dials have used IIII for centuries; it is a separate convention, not an error.
4. Look at a dial with a VIII opposite and the IIII will usually be there.
Exercice 11Approfondi3 points
Explain why 1990 cannot be written MXM, and give the correct numeral.
Afficher la correctionMasquer la correction
MCMXC
1. Subtraction is only allowed with I, X or C placed before one of the next two larger letters.
2. X may go before L and C only, so XM is not a legal pair.
3. Split 1990 properly: 1000 + 900 + 90.
4. 1000 = M, 900 = CM, 90 = XC, giving MCMXC.
Exercice 12Approfondi3 points
Put these in order, smallest first: XLIV, LIV, XLIX, XCI.
Afficher la correctionMasquer la correction
XLIV, XLIX, LIV, XCI
1. XLIV = 40 + 4 = 44.
2. LIV = 50 + 4 = 54.
3. XLIX = 40 + 9 = 49.
4. XCI = 90 + 1 = 91.
5. In order: 44, 49, 54, 91, so XLIV, XLIX, LIV, XCI.

Où l'on se trompe

Writing IIII or VIIII in written work where IV and IX are required, having seen IIII on a clock face.
Inventing subtractive pairs that do not exist: IL for 49, VC for 95, IC for 99, MXM for 1990.
Reading XC as 110 and CM as 1,100 by adding instead of subtracting.
Repeating a letter four times, so 40 becomes XXXX and 400 becomes CCCC.
Repeating or subtracting V, L or D — writing VV for 10 or LL for 100, neither of which the system allows.

There are six subtractive pairs and no others

Only I, X and C are ever placed in front of a larger letter, and each may only go in front of the next two letters up. I goes before V and X; X goes before L and C; C goes before D and M. That produces exactly six legal pairs, and every other combination people invent — IL for 49, VC for 95, IC for 99, MXM for 1990 — is outside the system.

V, L and D are never subtracted and never repeated. There is no VV, no LL, no DD, because V is simply half of X, L half of C and D half of M; doubling one gives a letter that already exists.

IV = 4 and IX = 9
XL = 40 and XC = 90
CD = 400 and CM = 900

Read a long numeral in place-value chunks, not letter by letter

MCMXCIV looks forbidding read one letter at a time and simple read in four pieces: M, CM, XC, IV — 1000, 900, 90, 4. Roman numerals are written strictly in descending order of place, so the chunks always come out thousands, hundreds, tens, units, in that order.

The same habit works in reverse. To write 449, split it into 400 + 40 + 9 first and convert each piece: CD, XL, IX, so 449 is CDXLIX. Trying to convert 449 in one go is where pupils end up writing CDXXXXVIIII.

The dial that prints IIII

Look at most public clocks and watches with Roman numerals and the four is written IIII, not IV. The dial is not wrong and the pupil who reads it as four is not confused — IIII is a long-standing clock-face convention that sits alongside, rather than inside, the written system taught in school.

No single explanation for it is agreed. The usual ones are visual balance with the VIII directly opposite, and the older additive form simply never being replaced on dials. Either way, it is a good demonstration that the subtractive rules are a convention rather than a law of nature.

In England, pupils read Roman numerals to 100 in Year 4 and to 1,000 in Year 5, where they are also expected to recognise years written in Roman numerals.

Subtractive pairs the system allows: IV, IX, XL, XC, CD, CM: 6Subtractive pairs the system allows: IV, IX, XL, XC, CD, CM
Letters in DCCCLXXXVIII (888), the longest numeral below 1,000: 12Letters in DCCCLXXXVIII (888), the longest numeral below 1,000

Questions fréquentes

Why is 4 written IIII on clocks but IV in books?

They are two conventions living side by side. Written Roman numerals settled on the subtractive IV, while clock dials kept the older additive IIII, and most dials still print it. Reading a dial correctly is not a mistake; writing IIII in a maths exercise usually is, because the question is testing the subtractive rules.

What is the largest number you can write in Roman numerals?

With the school convention that M is not repeated more than three times, the largest is 3,999 — MMMCMXCIX. Larger values needed extra notation, such as a bar over a letter to multiply it by a thousand, which is not part of what pupils are asked to read or write.

Is there a Roman numeral for zero?

No. The system has no symbol for zero and no way to write a negative number, because it records quantities rather than positions in columns. That is exactly what the English curriculum asks Year 4 pupils to notice: the number system later changed to include zero and place value, and the change is what made column arithmetic possible.

Which Roman numeral is the longest one my child will meet?

DCCCLXXXVIII, which is 888 and uses twelve letters. Nothing below 1,000 is longer, because 800, 80 and 8 are each the wordiest way their place can be written. It is worth converting once as a set piece — after 888, every other numeral looks short.

Sources

National curriculum in England: mathematics programmes of study — Department for Education

Dernière mise à jour 21 août 2026