10 Rules for Writing Numbers and Numerals

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?


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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210 thoughts on “10 Rules for Writing Numbers and Numerals”

  1. This article was most helpful, since much of the standard practice for using numbers in writing is simply convention on which we need to educate ourselves. But in the end, the purpose of all writing is to facilitate communication, and whatever promotes that goal is preferable. Many of the questions posed by the later posters above should be answered by stopping to think through that dictum.

    For example, Suzi (April 9) asks whether “ten inch (10″) nails or ten (10) inch nails” is proper for a legal document. I would answer that a legal document is above all about unequivocal precision, with far less emphasis on smooth flow of narrative style, and I would therefore write “ten-inch (10″) nails”. Note that the hyphen makes it clear that the nails are ten inches long, rather than there are ten 10″ nails involved. Writing “ten (10) inch nails” is even more confusing, because it could be construed as ten nails that are one inch long. So rather than get too bogged down trying to memorize a nearly infinite number of rules, just take a little time to stop and think about the various ways that what you wrote might be misconstrued. I think that is the key to all good proofreading, an art that seems to be dying out in our age of instant messaging and dashing off an email without bothering to review it.

    Another related point: the best format for good communication will vary according to the kind of document. An accounting or legal document is striving for unambiguity, and repeating a number in parentheses as suggested above or by Linda on July 28, 2009, would be appropriate. In a good novel, where the author is striving for a fluent style that draws the reader into another world and makes him forget that he’s just looking at words printed on the page, using the numeral repeated in parentheses would seem stilted and disruptive.

    Remember that English is a dynamic language that is arbitrary and inconsistent, in addition to always changing. Think about who is going to be reading what you are trying to convey, and then choose the form that will communicate what you intend most clearly and elegantly. Good writing takes a some time and work with the brain engaged!

  2. In a business letter, if you are telling a customer that he is “receiving a credit of ($15.00),” should the parentheses be used?

  3. The desire for precision in this post is admirable, but before the advanced level, shouldn’t we master the basics?

    There is no such thing as a quote. Quote is a verb, The noun is quotation.

  4. Hey, I wanted to know about how to write years is it ok if I write the year 1962 like this?

    One thousand nine hundred sixty two? or it has to be like this? nineteen sixty two?

    Please I really need to know this

  5. There are quotes not all of them brilliant though…:
    “Wonderful bargains for men with 16 and 17 necks.”
    – Sign in Men’s clothing store

  6. Where would I find help in writing out time? Specifically, I always understood that when the time is straight up, the “:00” is not used. Only when there are minutes should we write them out, even if there is more that one time used in the same sentence (9 a.m. or 6:15 p.m.). Is that correct or is it more important to just be consistent? And is there a correct way to write a.m. or p.m.? A.M or P.M.? Or either without the periods?

  7. I would like to know the answer to Shawne’s question as well. Is it AM or am, A.M. or a.m. or does it even matter?

  8. I need some advice- I have a sentence that must start with the name of a street= 6th Street. Do I have to spell out “Sixth Street” or can I use “6th Street” since that is the exact name of the street- please help.

  9. Capitals can change things. When writing “two”, you are supposed to “spell it out”; however, when writing “Plan 2” you use a digit. Irregardless of this rule telling you to spell it “6th Street”, if its name is “6th Street”, write it as “6th Street”.

  10. Shawne, I do not know the answer to the first part of your question. Fortunately I can help with the second part. “Ante meridiem” is Latin for “before midday”, and “post meridiem” means after midday. Periods denote spaces in Latin abbreviations (e.g. “i.e.” means “id est” and “e.g.” means “exempli gratia”); therefore, “ante meridiem” becomes “a.m.” and “post meridiem” becomes “p.m.”. This being said, writing it “am and pm”, “AM and PM”, or “A.M. and P.M.” are still acceptable (just not perfect).

    PS Although I do not know the answer to the first part of your question, I do know that in the 12 hour clock you write “noon” and “midnight” as opposed to numerals.

  11. Stephanie,

    it is spelled “nineteen sixty two”; however, it does not look great. Try to avoid starting sentences with years, so you can write, the more attractive, 1962.

  12. Dear J,
    Thanks for the help with the a.m./p.m. I never equated those with the Latin i.e. or e.g. Makes sense now to me (and Cindy as well, I’m sure). Perhaps someone will sign in eventually that knows the other part of my question…

  13. Thank you, Michael, for the useful info. I’ve always known about Rule 2 and it’s good that I can cite you as a good source, just in case 🙂 I’m into module writing and we title the module sections as Lesson 1 plus the title of the lesson. In this case, is it okay to write Lesson 1 instead of Lesson One? Thanks.

  14. I have always written numbers with a hyphen, such as: twenty-four and so on… but I have also seen without. Which one is correct or are both correct?

  15. I disagree with Peter, who must be across the pond

    “D R Brubaker and Carolyn are wrong about the “and” thing. The lack-of-and seems to be commonly taught in the US lately (I think it’s a very recent thing)”

    No, I’m over 65, and I have always been taught exactly what Carolyn said. No “and” is needed in expressing large whole numbers. I never thought of the “and” as a decimal, but I found others who mention that as well.

    Math teachers logic is different than English grammatical effect. The One Hundered and One Dalmations is not used as a counting phrase, but a descriptive title… It’s literary, not mathematical science here.

    In a strict mathematics sense the “and” is useless and misleading when expressing numbers. You have completely missed the point about her examples:
    307,000 = three hundred seven thousand
    (how many thousands? answer: three hundred seven)

    300.007 = three hundred and seven thousandths
    (how many? answer: three HUNDRED AND (a little bit more) seven thousandTHs)

    IF YOU WANT TO SAY 307/1000 you would say Three hundred seven thousandths. OK? not any of the above. It is distinct, and it is clear.

    You can see how the and helps to separate the whole part from the fraction.
    Carolyn: I’m not sure what you mean about reading the numbers aloud – they’re “three hundred point zero zero seven” and “three hundred and seven thousand”; what’s the confusion? Am I supposed to read “300.007″ as “three hundred and seven thousandths”? Even the difference between “three-hundred-and-seven thousandths” (307/1000) and “three-hundred and seven-thousandths” (300 + 7/1000) is only unclear in text (if you don’t hyphenate to clarify, as I’ve done here); it’s quite clear when spoken aloud (which is more like the hyphenated version – the timing is quite different).

  16. Sorry, the final paragraph below these
    was what Peter said. He has completely missed the point.

  17. I would like to know about the rule when you are writing a formal paper and there is a date in time such as March 4th 2007. Do I have to write that out in lettering or is it okay to write the numbers for both the date and year?

  18. When writing a given code with numbers and alphabet letters how can I differentiate the zero from the ‘O’letter? which one has the line through it – the zero would I imagine. !

  19. Well, the rules are made up by men. I think today everyone understands the evolution of languages together with how we use these languages. We create a lot of rules for convenience!

  20. Please help me. Does the use of commas in amounts apply to foreign currencies in an English article For instance, R$ 1.000 in Portuguese would change into R$ 1,000 if the article is in English? (R$ is the symbol for Real, the Brazilian currency)

  21. In technical writing, brackets around the number is often used.
    i.e There is a (5) second delay between the conveyor starting and the valve opening.
    What are your thoughts on this?

  22. I typeset a quarterly for a university department. The number of contributors can be from 8 to 20, and their papers are in several European languages. When I first received the Word files from the authors one of the first things I noticed was that the expression “the sixteenth century” (or anything of the kind) was written in English in several ways (XVI c.; XVIth c.; XVIth century; the 16th century, and so on and so forth). With a view to uniforming the expression, I decided to change all variants into “the XVI century”: the editor of the quarterly has observed that the majority of the contributors (most of them French) don’t like my choice because it is seldom used, and they prefer to change it into “the XVIth century”. In Italy the use of “XVI° secolo” is rightly considered wrong since the roman letters are naturally ordinals and don’t accept the small circle the end: it should always go with cardinals to transform them into ordinals. The same applies to British usage (as I have read in various English grammars). Sorry for the longish letter. What is your opinion?
    Very interesting this site of yours. I have already bookmarked it.

  23. All major publications have their own style guides, and they all conflict on this topic. When in doubt – go with the style manual of the publication you’re targeting.

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  26. my problem is with the hyphen in fractions.
    one-third, fine.
    but 21,87?
    is it twenty one and eighty seven hundredth or is there a hyphen (or two) to use in the “eighty seven hundredth” part?
    thx, guys.

  27. @Shawne:

    First question: yes, write 9 a.m.
    Second question: typographically, small-caps are preferred, so it looks like “A.M.” but is the same height as lower-case; that’s often turned into upper-case in “typewritten” text (i.e., where small-caps are not available), and eventually that turns into capitals even when small-caps are available (the same thing happened with the operating system often (mis)written “UNIX” — it’s supposed to be “Unix” with “nix” in small-caps, or perhaps all in small-caps), but I’d generally go with lower-case when you don’t have small-caps.

    @Marilyn: I disagree with Peter, who must be across the pond


    No, I’m over 65, and I have always been taught exactly what Carolyn said.

    Well, anything post-WWII fits into my definition of “very recent”, but Carolyn mentioned that “I can remember the days as I grew up, when “and” was spoken in every 321 or 507”, so unless Carolyn is a good deal older than you it doesn’t seem to have been universal.

    307,000 = three hundred seven thousand
    (how many thousands? answer: three hundred seven)

    Three hundred and seven thousand. How many thousands? Three hundred and seven. What was your point?

    300.007 = three hundred and seven thousandths

    First, I would never read it that way. I’d say “three hundred point zero zero seven” (and if you wrote it as a fraction I’d say “seven over a thousand”, not “seven thousandths”). Second: it doesn’t matter anyway because “three hundred” isn’t at issue: make it 302.007, and if you force me to say “seven thousandths” I’d read it as “three hundred and two and seven thousandths”, with “and” occurring twice (and there’s a short pause before the second “and”, which is destressed to point of being barely a grunt…)

    So no, I can’t “see how it helps”; quite the contrary! I know Americans talk that way, so I wouldn’t actually be confused on this point, but I’d want to interpret “three hundred seven” as two numbers: 300 and 7.

    (I wonder what you make of “four and twenty” blackbirds…or even “four score and seven” years…)

    @Vivienne: Which is correct – Writing letters is very popular in many parts of the world or Writing letters are very popular in may parts of the world.

    Presumably “writing” here is a noun (gerund), hence the subject is “writing”, not “letters”. Writing is singular, so you want “is”. (It could be interpreted with “writing” as an adjective modifying “letters”: if there were such as thing as a “writing letter” and these things were popular, then it would be “are”…)

    @J. Alcantara: Yes, write R$1,000 with a comma.

    @Mario: I agree, it should be “XVI century”.

  28. I need help with a letter to a university
    is this correct?
    “….would be responsible for seventy five percent (75%) of the tuition if withdrawal was made within the first three weeks of the quarter. I attended only one and one half (1 1/2) days of classes..”

    not sure about any of the numbers now

  29. So how would you write out –
    1 out of 24 cases resulted in …. OR
    One out of 24 cases resulted in ….

  30. I have to disagree with Jay on the first comment. The ONLY reason why AP didn’t use the % symbol is because teletype didn’t support it. This is the digital era so archaisms like that need to be broken.

  31. I just came here to check whether it’s correct to write out a number or not, but you guys have a huge discussion going on down here! Very interesting!

  32. I am editing a memoir that has a person’s age in it frequently. It is not written consistently and I would like to know the correct way to do it.

    For example, he says:
    “when I was nearing thirty-five”
    “I was 35-years old”
    “at age fifty”
    “before I was 21”
    “in my sixties” and “in my 60s”
    “between 25 – 30 years of age”
    “between twenty-five and thirty years of age”

    How should I be editing all of this?

  33. Wondering which is correct way to write time numbers less than ten in a formal sentence. Should one write “The clock struck at 1 am” or “The clock struck at one am.” Advice on the correct phrasing would be appreciated.

  34. Hey Jay (1st comment)

    You were quick to find something wrong with the article, so you could swoop in and save the day with your superior knowledge of numeral guidelines, which is wonderful, because we should all aim to challenge one another in a healthy and good-natured way, but you seriously left me hanging when you failed to explain to me “the rule of ten.”

    Personally, as a self-proclaimed writer whose mastery of the craft pales in comparison, I found this article to be fantasitc. It pretty much cleared up the questions that came up in my head EVERY single time I came across a number.

    That was before I got to the comments. Now I find out I may have been completely misguided, and I was just about to learn the truth and this is what I get. (Ready?):

    1.It’s called the ‘Rule of ten(10)’
    2. An example is: ‘Sadly, there were only eight computers available to the 23 students.’

    Excuse my ignorance, Jay but I’m not getting it.
    Damn, why did I read the comments?!

  35. get rid of spelling out numbers altogether.
    These are what we call traditions.
    They spawn when lots of people think the same.

    In many cases, they can be a shackle. Let people spell out numbers, but do not require it. Here are some reasons why:

    It’s more compatible with other languages to use numbers, it’s more productive and takes less time to write or type lots of numbers, and it’s really hard to read mathematical sentences like
    “ten-thousand and twelve times fourteen” rather than “10,012*14”.

  36. This discussion is very interesting, but what about when writing
    say, the numeral 7 followed by the written (seven)?
    eg. there were 7 (seven) horsemen, or should that be
    There were seven (7) horsemen??

  37. babu, the first one is correct in writing.

    Another general question: Why no mention of the Chicago Manual of Style? I do book proofreading, and the standard there for things like this is CMOS, which has a convoluted set of rules for how to use numerals in print. They suggest spelling out numerals up to ninety-nine in running text, with a gazillion exceptions for all sorts of mathematical and/or technical contexts, as well as mixing words and symbols in the same paragraph, etc. etc.

    I tend to now use their rules in most of my own writing. At the very least, I’m being internally consistent.

    Oh, and why does no one here put the period inside the closing quotation mark? So many comments here have it outside. That is U.S. standard. U.K. would put the period outside the quotation mark. Just asking! Too many U.S. folks get this wrong!

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