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# Thirty one or Thirty-one?

Thirty one or thirty-one?

In this article we show you how to write 31 in English words correctly.

In addition, we provide you with the grammar rule right away. 🙂

Regardless of where they appear in a number, hyphenate all compound numbers between 21 and 99 (not 30, 40, 50, 60, 70, 80, and 90) such as 31. In other words:

Hyphenate all numbers between twenty-one and ninety-nine, except those divisible by ten, even if the compound number is preceded or succeeded by numbers that do not require hyphens.
Thus, the correct spelling of 31 is thirty-one (hyphenated).

Along the same lines:
• 31,000 = thirty-one thousand (hyphenated).
• 31,000,000 = thirty-one million (hyphenated).
• 31,000,000,000 = thirty-one billion (hyphenated).

## Thirty-one or Thirty one Spelling

It doesn’t matter which noun follows the adjective, the grammar rule explained above remains in place.

In the examples below the correct spelling is underlined.

Thirty one years or thirty-one years?
Thirty one percent or thirty-one percent?
Thirty one hours or thirty-one hours?

### Does thirty one have a hyphen?

Yes, 31 has a hyphen and is spelled correctly as thirty-one.

### Do you hyphenate thirty one?

Yes, you put a hyphen between thirty and one: thirty-one.

### Does thirty one need a hyphen?

As 31 is a compound number in between 21 and 99 it needs a hyphen; therefore writing 31 in full is thirty-one.

In the table below we show you the correct spelling of some numbers succeeding and precededing 31:
NumberName
26twenty-six
27twenty-seven
28twenty-eight
29twenty-nine
30thirty
31thirty-one
32thirty-two
33thirty-three
34thirty-four
35thirty-five
36thirty-six

## Thirty first or Thirty-first?

In the following examples the correct spelling is underlined.

Thirty first part or thirty-first part?
Thirty first day or thirty-first day?
Thirty first hour or thirty-first hour?

• Does thirty first have a hyphen? Yes, the ordinal number for 31 has a hyphen and is spelled correctly as thirty-first.
• Do you hyphenate thirty first? Yes, you put a hyphen between thirty and first: thirty-first.
• Does thirty first need a hyphen? 31 is a compound number in between 21 and 99 which needs a hyphen. Thus, writing 31st in full is thirty-first.

## Thirty first or Thirty-one?

As you already know, 31 as cardinal numeral is thirty-one, and 31 as ordinal numeral is thirty-first.

Thus, the question in the subtitle above mixes two distinguished linguistic concepts and cannot be answered as such.

Observe that you can always check how to spell a number in full correctly using our converter below.

English:

American
British

To:

Words
Check
Currency

Letter case:

Sentence case
lowercase
UPPERCASE
Title Case
Spelling: Thirty-one

## Summary

As explained by the hyphens-in-numbers rule, 31 = thirty-one.

If you are happy with our information, then you may also be interested in our article thirty-three or thirty three.

We love to hear your feedback and answer any question about how to correctly write 31 you might have.

Thanks for visiting howdoyouspell.org.

– Article written by Mark, last updated on May 5th, 2023