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. All of the discussions and the “10 Rules for Writing Numbers…” is very informative, however, I came looking specifically for one apparently unwritten rule: How to write 3 or more digit numbers. For example I know it is incorrect to write or say one hundred AND three. It should be one-hundred-three. Sadly, I cannot find any reference to this. Someone please help me! I tried to point this out to someone on another blog and they refuse to believe me saying it doesn’t matter. I need a concrete rule or something of substance to reference to direct this misinformed “student.” Thank you.

  2. Would any body someone write the spanish numbers out for me.
    Also Send it to my E-Mail.

    Thank you all and ecspecially the person who lets me know how they are spelled.
    Shawn Plumley

  3. If you have a.m. or p.m. at the end of the sentence do you need a period?

    For example: The party starts at 7 p.m.

  4. I’m so late in finding your blog site. I am a fifth grade Math teacher. Let me see if I can add any clarity to a question from last November.

    Yes, it is correct to say one-hundred-three, not one-hundred-AND-three. This is as much “math” as it is “grammar”. In reading or speaking numbers, the word “and” is used to separate whole numbers and fractions or to separate whole numbers and decimal fractions. For example, 6 1/2 would be spoken “six and one half”; 21.03 would be spoken/read as “twenty-one AND three hundredths”. And, 307,000 should be read “three hundred seven thousand”, not “three hundred and seven thousand”.

    Read these two out loud: 300.007 and 307,000 to see how important an “and”, properly placed, can be. Because not everyone pronounces a good “th” on the end of fractions, the “and” is critical. Is it 121,000 or 100.021? Numerically, there is a huge difference.

    I teach my math students that the “and” indicates where to place a decimal point. It separates the “whole” from the “part”.

    Thus, from the first day of class, I do not allow any “ands” to be inserted in 397,241 when the number is being read aloud. (However, I can remember the days as I grew up, when “and” was spoken in every 321 or 507. That would really bother me now!) It’s a matter of getting your ear accustomed to hearing it spoken properly.

    I hope I’ve been helpful.

  5. Starting from the right, put a comma after every three numbers. For one thousand, write 1,000. For one million, write 1,000,000. It makes the number easier to read. In some cultures, a period is used instead of a comma.

  6. How do you write twenty five cents in business writing? Is it “25 cents”, ” $0.25″, “.25 cents”, ” 25C”, or something else? I ran across a business professional who said that the decimal point format with no zero before the decimal and the addition of the word “cents” is the correct way. Examples: .15 cents, .12 cents, .25 cents, etc. I disagree. These examples as I read them mean; 15/100 cents, 12/100 cents, and 25/100 cents, respectively. I thank you for your input.

  7. I agree with you: to me, “.25 cents” sounds like 1/4 of one cent. Exactly how you would write a fraction of a dollar depends how official or formal your document is. For accounting purposes, “$0.25” leaves no doubts about what you mean: 25 cents or 1/4 of $1.00. Informally, at least in the US, you could say, “a quarter”. “25 cents” would also be clear to me.

    Speaking of money, when writing a check for $100.25, you should always write it out as “one hundred and twenty-five/hundredths” not “one hundred twenty five” which means $125. The “and” acts like a decimal point, as far as bankers are concerned.

  8. Kirk: I suggest 25¢, personally. To find the “hidden” ¢ key, all you have to do is press alt + 155 on the number pad. The number pad is the important part. It won’t work on the number “line” on top of the keyboard.

  9. I agree with your analysis Michael. Thank you for the verification. I also want to thank Heidi for the info on the “¢” function on the keyboard.

  10. What about numbers in a legal document? Do we wite out the number and then also put it in brackets after?

  11. Emmanuel says 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.

    You should also never, under any circumstances, say “seventeen point twelve”!! It’s pronounced “seventeen point one two”.

  12. If you have a.m. or p.m. at the end of the sentence do you need a period?

    A.m. and p.m. already have periods (full stops, in proper English :)), so I don’t know what you mean. Are you asking if you need two – like “the party starts at 7 p.m..” or something? Definitely not!

    I ran across a business professional who said that the decimal point format with no zero before the decimal and the addition of the word “cents” is the correct way.

    The person who told you that must work for Verizon 🙂
    (Google “Verizon doesn’t know how to count” if you don’t know what I mean…don’t be drinking coffee at the time or you’ll need to buy a new keyboard)

    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), though even US style manuals point out that “and” is more idiomatic; in non-US English, leaving out the “and” sounds very strange and stilted indeed (and note that the US titles of works like “The Hundred and One Dalmations” are not altered to “The Hundred One Dalmations”, the way other USified titles are; e.g., “Harry Potter and the Philosopher’s Stone” became “Harry Potter and the Sorcerer’s Stone” in its US incarnation).
    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).

    I’d add a couple of rules here: for large numbers, use words “ten billion” rather than “10,000,000,000”; but for very large numbers, use digits and scientific notation: write “1.8743987×10^163” rather than trying to name it (“eighteen trequinquagintillion seven hundred and forty three duoquinquagintillion nine hundred and eighty seven unquinguagintillion” or something equally ridiculous :))

  13. i often feel confuse when i have 2 using numbering in my writing,but this explanation help me so much…

  14. Is there a rule that says if you leave out the commas in a five or more digit numeral it is written incorrectly?

  15. Would encourage “understanding” as opposed to just being able to “do” mathematics. This prompts:

    “10 rules for writing numerals” or “10 rules for writing number names”; not, “10 rules for writing numbers”

    The learning path in elementary arithmetic can be smooth if the learner and teacher understand: 1) What ” number” is. 2) The difference between a number and a name for that number. and 3) Every number has many names.

    Sorry, am straying fom your purpose. Will add that saying “three point five” instead of “three and five tenths” does not encourage understanding.

  16. To the person above who pointed out that UK is in Europe – you are correct, but the article says ‘Continental Europe’. It is my understanding that Continental Europe is not commonly understood to include the British Isles (or Iceland for that matter, I presume).

    It is true that in France, for example, they use commas where we would use decimal points, but the UK (where I live) uses decimal points and commas in the same was as the US. The author was careful to say ‘Continental Europe’, thus he is still correct 🙂

  17. Questions from a police officer’s test…and wondering what is right?
    I went through PA’s act 120 and I am now submitting applications & taking tests, but these questions keep coming up & I don’t recall covering any of this material.
    Is a a suspect 49 years old, or forty nine years old?
    Is he six feet two inches tall, or 6′ 2″ tall?
    Is the correct time 8:22 PM, or 20:22?
    Any help is appreciated.

  18. Betsy Lucas asks, ” Is the correct time 8:22 or 28:22 ? Really cannot say. But if “8:22” is read “eight twenty-two” why is “8:07” read “eight oh seven” instead of “eight seven” or at least “eight zero seven” ? My point: “zero”, a name of a number, and the letter “O” are not interchangeable.

  19. Okay, here’s my burning question: what is the name of the decade we’re in? Eight years into it, I still don’t know. The Oughts? The O-ies?

  20. The rules stated here are correct, that is, they conform to the established rules, but the truth is these rules are not the way to write numbers the most clearly. Numerals are much easier to read than spelled out numbers, and I find “percent” instead of “%” to be a major aggravation. Sometimes I even use search and replace to change it, when I am copying snippets for my own use.

  21. Thank you so much for the info on money! I have been trying to get my children to not put the decimal point for change when using the ¢ sign, now I have a real rational for why not to do it! Thanks, also for the (alt +155) tip…I also found that in Microsoft and OpenOffice applications (alt + 0162) works as well (both with and without using the number pad)

  22. You know how you tell yourself you are studying because you have your certification books opened in front of you? But you are really clicking on Stumble Upon to find interesting posts to read?

    Yeah well, I came across yours and had to write to tell you I enjoyed it very much. I gave it the thumbs up, so more people can come across it and enjoy it also.

  23. I agree with Mike (July 31st, 2007 7:43 pm) that it would be aesthetically pleasing to make the title of this article “Ten Rules…” not “10 Rules…”. Even if it is a title rather than a sentence, it looks strange in relation to rule #5: “Don’t start a sentence with a numeral”. Is there anything to justify the use of a numeral here instead of spelling out this highly readable short word?

  24. Need help please…which is correct?

    Eleventh Annual Surgical Forum or
    11th Annual Surgical forum


  25. Hi,

    I have a question. When writing a letter with dollar amounts that doesn’t have cents, which way is correct; thirty six dollars, $36 or $36.00. Here is part of the letter that is sent; Thank you for your most recent gift of $1,000 ………..

    Thank you.

  26. Great article. I only read it because the title had the number 10 numeralized rather than spelled out. I most definitely like numbers (er, numerals).


  27. Rod,
    The comma suggests that the reading should include the words, “three thousand”. Consider: “3300” is sometimes read (for what purpose I know not), “thirty three hundred”. Would that person read “330” by saying, “thirty three tens” ?

  28. How should I use nought? Is it true that I need to say it if there’s a zero after a point for decimals? for example 0.002

  29. When writing a formal announcement or invitation, should the number be capitalized and/or hyphenated? …as in “…respond by the twenty-fourth of September…”

  30. I would like to know, when spelling a number in any document should we also write the number in parat. ex : I bought six (6) dresses.


  31. Do you have to write a comma between each group of place values when writing a number in word form? For example, is 4,305 written four thousand three hundred five or four thousand, three hundred five. Is the comma necessary?

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