when to write numbers header

Wondering whether or not you should spell out the numbers in your school report, novel, or blog?

It can be difficult to keep the rules straight, especially when we see different styles used all across the internet or in our casual correspondences. But we’ve broken down the rules for you with this simplified guide so you never have to wonder again!

Spelling Out Numbers: The General Rule

The most generally accepted rules for writing out numbers in non-scientific and non-technical contexts are as follows:

  • Spell out all numbers between zero and ten.
  • When numbers are used to start a sentence, they should always be spelled out.


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When dealing with technical or scientific writing, numerals can be used for all numbers above ten. 

(Numerals are symbols that are used to denote numbers, such as 1, 2, 11, 23…)

However, the most important thing to remember in any kind of writing is consistency. Even if your chosen style differs from this general rule, what matters is that you stick with that style throughout your writing.

Style Guides

Some style guides offer their own specific rules for spelling out numbers. If you have a designated style guide, be sure to always reference that when in doubt.

Chicago Manual of Style

The Chicago Manual of Style lays out the following rules for spelling out numbers:

  • Spell out numbers zero through one hundred
  • Use numerals for numbers over one hundred
  • Spell out certain round numerals, specifically: whole numbers one through one hundred followed by hundred, thousand, or hundred thousand), except in monetary amounts or percents


  • Seventy-two
  • One thousand
  • Two hundred thousand
  • Seventy thousand
  • Two hundred
  • 72 percent
  • 101

Additionally, when two numbers need to be placed next to each other, it’s best to spell out one of them (usually the smaller amount).


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APA Style Manual

The APA Style Manual lays out the following rules for spelling out numbers:

  • Spell out numbers below 10
  • Use numerals for numbers 10 and greater


  • Three
  • Seven
  • 11
  • 100

MLA Style Manual

The MLA Style Manual lays out the following rules for spelling out numbers:

  • Spell out numbers that can be written with one or two words
  • Use numerals for all other numbers


  • One thousand
  • Fifteen
  • Seventy-two
  • 1,500
  • 72,100
  • 187

Numbers in Blogs

If you write blog posts, your company might have a preferred style for you to use. But if it’s up to you to decide, the following suggestions might help:

  • Spell out numbers from zero to nine
  • Use numerals for numbers ten and greater
  • Don’t start sentences with numerals
  • Headlines that start with numerals (such as “7 Tips…”) tend to generate more social shares and engagement

When to Hyphenate Numbers

If you do need to spell out larger numbers, a hyphen might be necessary. See the following rules:

  • Always hyphenate compound numbers between twenty-one and ninety-nine (this does not include numbers ending with 0)
  • If you need to write out numbers higher than ninety-nine, do not use a hyphen; use “and” instead


  • Sally is thirty-three years old.
  • Forty-seven candidates were accepted last year.
  • Three hundred and forty-two dogs were rescued.

Numbers or Numerals?

To keep your writing clear and consistent, it’s important to know when to spell out numbers and when to use numerals.

When in doubt, always refer to your designated style guide for the most clear details and rules.

Did you find this article helpful? Let us know in the comments below!


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