31 in Roman numerals at a glance
- Roman numeral
- XXXI
- Lowercase
- xxxi
- Letters
- 4
- Parts
- X · X · X · I
- Subtractive pairs
- None
- In words
- thirty-one
- Latin name
- triginta unus
How XXXI is built
Roman numerals are written one decimal place at a time, from the largest place to the smallest. Converting each digit of 31 separately and joining the pieces gives XXXI:
| Place | Digit | Value | Numeral |
|---|---|---|---|
| Tens | 3 | 30 | XXX |
| Ones | 1 | 1 | I |
Reading it back, left to right:
- X = 10 → running total 10
- X = 10 → running total 20
- X = 10 → running total 30
- I = 1 → running total 31
The rules XXXI follows
- Largest to smallest. XXXI uses the symbols X and I (4 characters in all), and the values never increase from left to right except inside a subtractive pair.
- No subtraction needed. None of the digits of 31 is a 4 or a 9, so XXXI is purely additive: just add the symbol values.
- Repetition. XXX repeats X three times. I, X, C and M may repeat up to three times in a row; V, L and D never repeat.
Where you will see XXXI
- The modern Summer Games. They are officially numbered by Olympiad; the Games of the XXXI Olympiad belong to 2016: Rio de Janeiro.
- Championship games. Pro football numbers its championship game with Roman numerals, starting from game I in January 1967. Game XXXI was played in early 1997.
- Volumes and sequels. Book volumes, conference editions, film sequels and anniversary events often carry a Roman numeral; edition XXXI would be the 31st.
Numbers near 31 in Roman numerals
Frequently asked questions
How do you write 31 in Roman numerals?
31 is written XXXI. Break it into X (10), X (10), X (10), I (1) and add the parts: 10 + 10 + 10 + 1 = 31.
What is 31 in Latin?
The Latin cardinal number 31 is “triginta unus.” The Romans wrote it as XXXI.
What is XXXI plus one?
XXXI + I = XXXII (32). Adding one can change the whole ending of a numeral, which is why it helps to convert to digits, add, and convert back.