31 in Words
How do you write 31 in words?
The number 31 is written thirty-one in words. As an ordinal it is thirty-first, and on a check you would write Thirty-one and 00/100.
Last updated 24 August 2026
Other ways to write it
| Cardinal | thirty-one |
|---|---|
| Ordinal | thirty-first |
| Currency | thirty-one dollars |
| Check format | Thirty-one and 00/100 |
How 31 is written
31 is the sum of its place values, 30 + 1, and is written thirty-one.
Its ordinal form is thirty-first — only the final element takes the ordinal ending — and on a check the amount line reads "Thirty-one and 00/100", where 00/100 stands for zero cents.
The hyphen in thirty-one is required: English hyphenates every compound number from twenty-one to ninety-nine.
For house-style rules on spelling out numbers, see the Chicago Manual of Style.
Facts about 31
- 31 is an odd number.
- It is a prime number.
- Digit sum: 4.
- Roman numerals: XXXI.
- Binary: 11111.
- Hexadecimal: 1F.
| Digit | Place |
|---|---|
| 3 | tens |
| 1 | ones |
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Frequently asked questions
How do you write 31 in words?
31 in words is "thirty-one".
How do you spell 31?
31 is spelled "thirty-one".
How do you write 31 on a check?
On a check, write "Thirty-one and 00/100".