Why the 31 part uses a hyphen
Compound numbers from 21 through 99 join the tens word and the ones word with a hyphen. In 31, the 31 part combines thirty and one, producing thirty-one.
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31 in words is thirty-one.
| Style | Words |
|---|---|
| American English | thirty-one |
| British English | thirty-one |
Compound numbers from 21 through 99 join the tens word and the ones word with a hyphen. In 31, the 31 part combines thirty and one, producing thirty-one.