Number
31 in Roman numerals
31 is written XXXI
Type any other number or numeral below to convert it.
Above 3,999? Type the barred part in brackets, e.g. (IV)CC = 4,200.
How XXXI is built
Roman numerals are written one decimal place at a time, largest first.
- XXXtens · 3X written 3 times: 3 × 10 = 30.
- Iones · 1I is 1.
30 + 1 = 31
No subtraction is needed here: every letter is the same size or smaller than the one before it, so you simply add them up.
About the number 31
- 31 is a prime number: only 1 and 31 divide it exactly.
- XXXI has 4 letters. 784 of the numbers up to 1,000 have longer numerals.
- As a day of the month, XXXI is the 31st. Write a date
Counting from 31 to 40
| Number | Roman numeral |
|---|---|
| 31 | XXXI |
| 32 | XXXII |
| 33 | XXXIII |
| 34 | XXXIV |
| 35 | XXXV |
| 36 | XXXVI |
| 37 | XXXVII |
| 38 | XXXVIII |
| 39 | XXXIX |
| 40 | XL |