21 in Roman Numerals
Twenty-one is written XXI in Roman numerals. You read it left to right, adding each glyph in turn: X for 10, X for 10, I for 1.
How XXI is formed
Reading left to right, 21 breaks into these additive parts. Each Roman symbol is added in turn to reach the total.
X + X + I = 10 + 10 + 1 = 21.
Where 21 in Roman numerals is used
- Chapter, act or appendix numbering in books and plays.
- Super Bowl XXI and other numbered championship events.
- Outlines, exam questions and list items in formal documents.
- Monarch and pope names, for example the 21st of a royal line.
Good to know about 21
- Twenty-one, XXI, is the coming-of-age numeral in the US and the name of the card game.
Convert another number
21 is written XXI in Roman numerals.
Frequently asked questions
How do you write 21 in Roman numerals?
Write 21 as XXI, combining X + X + I. Start from the largest value that fits and work down until nothing is left over.
Which Super Bowl is XXI?
Super Bowl XXI is the 21st Super Bowl, played in 1987. The NFL sets its championship number in Roman numerals, which is why so many people look up values like XXI.
What number is XXI?
XXI is 21. Read the symbols left to right, treat any smaller-before-larger pair as a single subtraction, and add the groups together.
Is there a shorter way to write 21?
No. XXI is the standard, canonical spelling. Each value has exactly one correct Roman form, so XXI is the only valid way to write 21.