How do you write 21 in Roman numerals?

21 is written as XXI in Roman numerals: 21 = 20 (XX) + 1 (I). The symbols are then written from largest to smallest value.

What does XXI stand for?

XXI stands for the number 21. Reading left to right: XX = 20, I = 1.

How do you write "21st" in Roman numerals?

Ordinal numbers use the same numerals as cardinal numbers, so "21st" is written XXI — Roman notation has no separate ordinal form.

21 in Roman Numerals

How to write the number 21 in Roman numerals, with the full place-value breakdown.

The number 21 in Roman numerals

XXI

Place-value breakdown

21 = 20 + 1, so XXI = XX + I. Roman numerals are written from largest to smallest value, left to right:

Place	Value	Roman	Rule
Tens	20	XX	Additive rule: XX = 20 (symbols are simply added)
Ones	1	I	Additive rule: I = 1 (symbols are simply added)

About the number 21

The number 21 is written XXI in Roman numerals.

Looking for the ordinal form — "21st in Roman numerals"? Roman notation makes no distinction between cardinal and ordinal numbers, so "21st" is also written XXI.

Convert any number

Number (1-3999)

Roman numeral

XXI