10 Rules for Writing Numbers and Numerals

By Michael - 2 minute read

How do you express numbers in your writing? When do you use figures (digits) and when do you write out the number in words (letters)? That is, when do you write 9 and when do you write nine?

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1. Number versus numeral. First things first, what is the difference between a number and a numeral? A number is an abstract concept while a numeral is a symbol used to express that number. “Three,” “3” and “III” are all symbols used to express the same number (or the concept of “threeness”). One could say that the difference between a number and its numerals is like the difference between a person and her name.

2. Spell small numbers out. The small numbers, such as whole numbers smaller than ten, should be spelled out. That’s one rule you can count on. If you don’t spell numbers out it will look like you’re sending an instant message, and you want to be more formal than that in your writing.

3. No other standard rule: Experts don’t always agree on other rules. Some experts say that any one-word number should be written out. Two-word numbers should be expressed in figures. That is, they say you should write out twelve or twenty. But not 24.

4. Using the comma. In English, the comma is used as a thousands separator (and the period as a decimal separator), to make large numbers easier to read. So write the size of Alaska as 571,951 square miles instead of 571951 square miles. In Continental Europe the opposite is true, periods are used to separate large numbers and the comma is used for decimals. Finally, the International Systems of Units (SI) recommends that a space should be used to separate groups of three digits, and both the comma and the period should be used only to denote decimals, like $13 200,50 (the comma part is a mess… I know).

5. Don’t start a sentence with a numeral. Make it “Fourscore and seven years ago,” not “4 score and 7 years ago.” That means you might have to rewrite some sentences: “Fans bought 400,000 copies the first day” instead of “400,000 copies were sold the first day.”

6. Centuries and decades should be spelled out. Use the Eighties or nineteenth century.

7. Percentages and recipes. With everyday writing and recipes you can use digits, like “4% of the children” or “Add 2 cups of brown rice.” In formal writing, however, you should spell the percentage out like “12 percent of the players” (or “twelve percent of the players,” depending on your preference as explained in point three).

8. If the number is rounded or estimated, spell it out. Rounded numbers over a million are written as a numeral plus a word. Use “About 400 million people speak Spanish natively,” instead of “About 400,000,000 people speak Spanish natively.” If you’re using the exact number, you’d write it out, of course.

9. Two numbers next to each other. It can be confusing if you write “7 13-year-olds”, so write one of them as a numeral, like “seven 13-year-olds”. Pick the number that has the fewest letters.

10. Ordinal numbers and consistency. Don’t say “He was my 1st true love,” but rather “He was my first true love.” Be consistent within the same sentence. If my teacher has 23 beginning students, she also has 18 advanced students, not eighteen advanced students.

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209 Responses to “10 Rules for Writing Numbers and Numerals”

  • Jay Wagers

    Most of these are correct. But, concerning 7, the percentage symbol should not be used in everyday writing. The percentage symbol is for business use, such as visual presentation. In other forms the word “percent” should be used. Also, your example in 10, concerning the students, is correct because the numbers are related. But, if the numbers aren’t related, then the “rule of ten” applies. Here’s an example: Sadly, there were only eight computers available to the 23 students.

    As always, the tips provided here are valuable for many. That’s why I keep coming back “daily.”

  • Daniel

    Jay, good point on number seven. I think you should use digits for everyday writing and spell the percentage out in formal writing (like a newspaper article). I added this remark.

  • dailytri

    I believe there is a rule on using numbers with age as well, right? As in “always use figures to represent the age of a person.”

  • Shankar

    I was not aware of those of these rules, cool.

  • Berto

    Is the comma used as a thousand separator everywhere English is spoken, or is that just an American rule?

  • Daniel

    Berto, that is the English standard, so it should apply both to UK and US.

    Notice, however, that some places around the world use the dot as a separator and the comma to denote decimals.

    To add confusion, the International System of Units recommends to use spaces to the sets of three digits, and use the comma or period just for the decimal.

    I just added this info to the post, thanks for asking.

  • Deron Sizemore

    #2 is one that I always have a dilemma with. I know with AP style writing you’re suppose to write numbers you’ve stated in #2. In MLA style, you write one, five, twenty-one, one hundred, eighteen hundred, but write 5½, 101, 3,810. I actually like the AP style better with writing out one through nine and ten on, writing it as 10, 11, 12, etc.

    I am curious though, your #2 you said “The small numbers, such as whole numbers smaller than ten, should be spelled out.” Why have you not wrote 10 as “10” since only numbers smaller than 10 should be spelled out?

  • Michael

    Oops, that would make sense. But see rule #3!

  • Daniel

    Deron, point two says that all whole numbers smaller than ten should be spelled out. It does not say anything about number equal or greater than ten. In fact, if you then read point 3 you will see that there is no standard rule for those numbers, some authors like to write them in digits, others still prefer to spell them out.

  • 60 in 3

    Heh, now I feel bad for naming my blog 60 in 3. Oh well, thank you as always for the great tips.

    Gal

  • van

    Firstly:
    1. Number versus numeral. First things first, what is the difference between a number and a numeral? A number is an abstract concept while a numeral is a symbol used to express that number.

    Then:
    5. Don’t start a sentence with a number. Make it “Fourscore and seven years ago,” not “4 score and 7 years ago.”

    Shouldn’t that be:
    5. Don’t start a sentence with a NUMERAL.

    Last time I checked, “four” and “4” where both numbers…

  • Daniel

    van, number 5 is fixed, thanks for the heads up.

    Then, “four” and “4” are both numerals used to express the concept of “fourness,” they are not numbers themselves, they are symbols.

    It is quite confusing I know, and probably not useful for the average writer. The other rules do apply though.

  • Michael Alexander

    I suppose it depends what grammar book you want to fall back on, but it would easy to argue that you’re flat-out wrong about when to spell out numbers.

    Use numerals before anything that can be measured: 3 decades, 3 years, 3 GB but not 3 children.

    Use numerals when using a single digit number and a number composed of two or more digits in the same sentence. “Bob ate 3 cows and 12 pigs,” not “Bob are three cows and 12 pigs.”

    One more for your list: Spell out any number used in a quote: “…four score..” and not “…4 score..”

  • Daniel

    Michael, 3 years you say? Well, here is a quote from the NY Times:

    “Dobbs’s correspondents said there had been 7,000 cases of leprosy in this country over the previous three years, far more than in the past.”

  • Bill

    “the difference between a number and its numerals is like the difference between a person and its name”

    ..a person and his name
    or ..a person and her name
    but never ..a person and its name

  • Daniel

    Bill, fixed that. I was thinking about an object and its name 🙂 , like the words that define it.

  • Emmanuel

    What I think it boils down to is: try writing the numerals in words; chances are that’s the right way. If words are obviously more confusing than digits, use digits. For example: “the second chapter”; “she’ll be eleven years old in two days”; “it’s the third road down the right”. These are all correct. But “seventeen point twelve percent of the data applies to all of our six hundred and forty two units and the rest only concerns the items that are stored in area three seven two” is confusing, and the numbers here should be written in digits. It’s more flexible than the rules above, but it follows the same spirit.

  • Jason

    The comma is an English rule, so it must apply in the US as well.
    (NOT the other way about)

  • James

    #4: The UK is in Europe. We do not use a comma as you describe. Thanks anyway.

    Also whilst we’re talking about international numbering, isn’t it about time that the USA moved on from imperial measurements to metric like the rest of the world?

  • Daniel

    Good point Emmanuel, common sense should help here as usual.

  • Abdullah

    I didn’t know about all the rules. I visited this for the first time but I liked it. I will visit it regularly.
    Keep it up.
    Thanks

  • Deron Sizemore

    Hey Daniel, thanks for pointing that out. My mistake on misreading what was there. 🙂

    With that said, since there is not standard rule, what is your own personal preference?

  • Dan Zambonini

    I’ve been reading quite a bit about typography lately, which has impressed on me another rule that you should add to your list:

    In the flow of a typical sentence (i.e. for ‘inline’ numbers), you should use “lower case” numbers.

    http://www.adobe.com/type/topics/info5.html

    Yes, you can have lower case numbers!

  • Michel

    @James And about time the UK used kg instead of stone to denote body weight

  • David

    James, enjoy 2.5 dl of tea

  • Jack Doyle

    You can write it out when it is two words or less. Twenty is acceptable. Twenty-four is acceptable. If it requires more than two words, you should use the numbers.

  • Nitro

    So you say to spell out twelve, but then you say “12 percent”? Shouldn’t it be “twelve percent”?

  • Daniel

    Nitro, we are not saying you should spell out twelve. The only standard rule, as stated in point one, is to spell out whole numbers smaller than ten.

    Other than that it is up to the author and his preference for the specific situation.

    Personally I like use digits above the number te because it makes the text more clear, like “15 percent.” For smaller numbers you can spell them out though, like “five percent” or “two percent.”

  • Steve

    These standards are good for English, but why not broaden the standard to multiple languages?

    Why not just remove spelling out of numerals completely and standardize on using Arabic numbers? Then the numbers would never have to be translated except to traditional less used numbering systems. Then people who read the articles in foreign languages like French, Spanish, Hindi, Chinese, Russian, and a plethora more could understand without mentally having to translating from the English naming convention into their own numerical naming convention.

  • Everton

    gr commenent Pascal-its g 2 c read comments from ppl with g sense of humours. ur a *!

    Out of interest how would write operators?

    PS you need a subscribe to comments option

  • Daniel

    Everton, it is on the “to do” list 🙂 .

  • Marc Savoy

    Thank you very much for providing this very valuable lesson in writing skills I’ve always wanted to acquire.

  • Jeremy Dalton

    Good tips. I’m enjoying this website quite a bit. 🙂

    One more point I’d add, though, is using numerals for lists. It helps one remember the number itself more easily than if you had spelt it out, and aids quick comparison. E.g.,

    3 eggs
    4 cartons of milk
    1 roast duck
    2 oranges

  • Mike

    Don’t you think the title should have been Ten Rules for… instead of 10 Rules for … considering your own guidelines?

  • Daniel

    Mike, usually titles have different rules, as far as typography goes at least (we should have covered that perhaps).

    Like titles usually have all the words starting with capital letters, you don’t write that way normally.

    That said, even if you consider our guidelines the “10 Rules” is congruent with points two and three. They state that numbers smaller than ten should be spelled out, and after that it is preference of the author.

  • Mike

    Thanks Daniel. As you mentioned that titles have different rules. I feel the title should start with a word. It looks more aesthetically pleasing. Not sure whether anyone agrees with me.

  • Daniel

    Mike, I agree with you 🙂 . Maybe starting the title with a word is more pleasant, I will research about it and even experiment with it in the future.

  • P. Dant

    You shouldn’t write “percent” ever. It’s wrong like “etcetera” is wrong. Put the space between the words: “per cent”.

  • mark

    Very well written list.
    Now if we could teach all newscasters and advertisers how to SAY numbers I would be in heaven.
    Seems they all got stupid in the year two thousand AND one.

  • Daniel

    P. Dant,

    It is funny when people come and say: “hey, you should not say that, ever!” or “you are dead wrong here!”

    Just make a quick search on the net before posting such strong statements.

    Per cent is the preferred British form, and percent is the American usage. Open the NY Times or the Wall Street Journal and you will find “percent” everywhere.

    Thanks for the comment though, it served the purpose of clarifying this point.

  • Nishanthe

    Good post!
    There were many points, which I havent known until I read this article. But seems some of these rules are not practicable special ‘dot’ and ‘comma’ rule.
    -Nish

  • FavHost

    I never really new there was a difference. Thanks for the post. Very informative!

  • Dora

    What is correct:
    “It’s my 13th birthday” or “It’s my thirteenth birthday”?

  • mohamed abu shatrar

    idnt speak

  • raullugo

    I like to know how to write the number seven hundred two thousand, three

  • yasmin

    as i am the first visitor of this web site so i have no comment writs now .

  • thursday

    what about: 24-7 (VS) twenty-four seven ??

  • Irene Stamatelakys

    How would you write 1.5 to 2 acre lots?

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  • Sonny

    Which is correct?

    We celebrated our ninth birthday party together.
    We celebrated our ninth birthday partys together.

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