Roman Numerals 1-20
Chart from romanumerals.com/numbers/1-20
Need a number above 20? Use the converter.
The pattern
- From 1 to 20 you only need 3 symbols: I (1), V (5), and X (10).
- 4 numbers use subtraction: 4 (IV), 9 (IX), 14 (XIV), and 19 (XIX). In each one a smaller symbol stands before a larger one and is taken away from it.
- 1 to 3 repeat I. 4 is one before five (IV), 6 to 8 add I's after V, and 9 is one before ten (IX).
- 11 to 19 are X followed by the numerals for 1 to 9: XI, XII … XIX.
- The longest is 18, XVIII, with 5 letters.
Common mistakes
Wrong: VIIII
Why isn't 9 written VIIII?
A symbol can repeat at most three times in a row. The correct form is IX: X − I.
Wrong: IIX
Why isn't 8 written IIX?
Only one smaller symbol can come before a larger one. The correct form is VIII: V + I + I + I.
How to remember them
- Learn 1 to 10 first: everything up to 20 is X followed by one of those (XIII = X + III).
- Group by fives: V is a hand, X is two hands. 15 is X + V, written XV.
- When a smaller symbol comes before a larger one, subtract it (XIV, XIX); otherwise, add it.
Try it
Five numbers from this list. Answer in your head, then open the answer.
1.How do you write 4?Show the answer
IV
2.What number is XIII?Show the answer
13
3.How do you write 18?Show the answer
XVIII
4.What number is V?Show the answer
5
5.How do you write 14?Show the answer
XIV
Where you will see them
Clock faces with Roman numerals very often show four o'clock as IIII instead of IV, although some, like the Elizabeth Tower clock in London, use IV. Why clocks use IIII.
Some documents still write the month in Roman numerals so it is not mixed up with the day, from I for January to XII for December. Ireland used them for the month on postage franking until the late 1980s.
Common questions
Which numbers from 1 to 20 use subtraction?
4 (IV), 9 (IX), 14 (XIV), and 19 (XIX): 4 numbers in all.
What is the longest Roman numeral from 1 to 20?
XVIII (18), with 5 letters.