10 Rules for Writing Numbers and Numerals

By Michael

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

  • Sara

    I’ve always spelled out any number less than ten, since that is what I was definitely taught by my wonderful journalism teacher in high school. What I’m curious about today, is how to correctly write “3+” as in you need three or more years of experience. (Did I just answer my own question? Ha!)

  • Vivian

    Also, when expressing whole dollar values, you do not add the decimal sign with two zeros. For example, you would write $10/hr. or $10 per hour, omitting the decimal sign and zeros.

  • Jenn-NOLA

    Linda asks, “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!”

    We prefer to use the term “conventions” rather than “rules” of right or “wrong”. The problem with the US “standard” for placing the end punctuation inside quotation marks is that it is inconsistent and illogical. The “rule” was established when type was set by hand and the little “.” would have fallen out if it were not wedged under the ” ” ” symbol. In the 21st century, when little is printed and certainly very, very, very little is typeset by hand – went out with Molly RIngwald hairstyles and leg warmers of the 80s – it is time to place the punctuation logically and consistently. Examples: Did the document contained the word “the”? The document contained the word “the”.

  • Gunnar

    Dear ‘van on July 31, 2007 9:06 am’, both are numerals, too…

  • Bob

    I am calculating numbers for a math/physics problem to unprecidented precision. Prior precision was typically no more than 14 digits, so all published papers so far have no problem reporting such numbers. Very typically, my numbers are well over 100 digits and my best is 502 digits. Do you have any recommendations for how to report such numbers in a meaningful way? Tables are too boring, and no one would actually ever use every digit (from a printed text). I was thinking about reporting the first twenty and the last ten, with a pointer to a web-stored file. But, that is only an idea. Another secondary issue is that for one problem, I have calculated over 8000 such numbers, but those are only good to 60 digits. Documenting those numbers (to be verifiable in a printed journal) seems impossible (because of the sheer number of digits). Perhaps an md5sum of a file holding them all? Any ideas? People report algorigthms for calculating pi (not their trillions of digits), but that isn’t really possible for my numbers, at least in a simple way.

  • David

    to venqax:
    ” Why would you say someone is 183 cm, when you can say he’s six feet? ” Your point is?
    I can ask the same question, why would you say someone is 5ft and 10.8 inches, when you can say he is 1.80m?
    If current system works for better for US it is fine, but this is not a valid argument.

    “Do I type “a” or “an” before the number 120? Why would you ever use “an” before 120? “An one-hundred and twenty”, “an hundred and twenty”. “An one two zero”. Any would be equally wrong.”
    Not equally wrong, an “an” is required preceeding a word that phonetically starts with a vowel, e.g. an eight, an SAP company, an eight hundred pound man. However i will give you the point, and it is beyond my understanding why would yo need to express an one hundred, when you can say a hundred, but that is another discussion.

    By the way I am from Mexico where we use the metric system.

  • Jerry

    Which is correct English?

    – 1 of 10 or 1 out of 10

  • Reed Proctor

    You don’t use AM/PM for military time. 0800 AM is redundant. That would be like saying it’s 8 a.m. a.m. That’s what military time notation was designed for – to eliminate the question “Is that a.m. or p.m.?”

  • Uncle Bill

    In skimming through the responses I did not see a suggestion for an eleventh rule: spell out numbers within quotes and dialogue based on the notion that we speak in words and not in symbolic numerals. For example, “Jack said ‘I saw about four hundred of them on my last trip,'” rather than “Jack said ‘I saw about 400 of them on my last trip.'”

  • Thomas Garrod

    Dale Wood wrote, “(i.e. they are being paid).”

    Dale, you seem very competent in your grasp of punctuation, but I see you do not include the comma after i.e. Is this an British-English standard? In US English, we include the comma to reflect the ubiquitous (or is it obligatory) pause after “for example.”

    I can hear the argument for exclusion of the comma (e.g., conservation or “It’s shorthand, dummy!”), but is there a different unknown to me (is that even possible)?

  • Pandora

    I have never seen so much ado about so little. One rule applies every time and it is absolute in writing, “Spell out any number less than ten”.
    Oops, had to fix that.

  • NickTheNerd

    R.E. Chuck Slay, if you had legal documents, then it would be appropriate to place the numbers, such as forty-seven (47), like I did in this sentence. Otherwise, just follow these guidelines.


    I have a question concerning the slash marks that run through certain numbers when written, such as the number seven and zero. and in fact what is the proper way to write numbers in general? we have had quite the debate at work.
    I have always placed marks through my number sevens and zeros as well as through my letter Z’s

  • A. B.

    Rule # 9 is there a set rule to that? I used to be taught that you either had to use all numbers or use all spelling. Your ten rules has shed some light for me.

    Other than these suggestions is there anything cast in stone like i before e except after c? Otherwise it leaves a lot of ambiguity to some study I am doing.

    Thank you for your help. Great web site.

  • CJ

    @ Sonny
    I think “We celebrated our ninth birthday parties together.” is correct.
    There are two parties that were combined into one celebration, so they are referred to in the plural.

  • Diana Ann Bisares

    I’m not sure if it’s worth mentioning, but there’s an exception for rule #1: dates. We say “December 9” and not “December nine.” Unless I’m not aware of some other rules?

    Anyway, thanks for this article, Michael. For non-native speakers like me, it’s very helpful to have easy access to grammar guidelines like this. 🙂

  • Chuck Slay

    I am helping a police officer apply for a promotion. He has worked 33 years in narcotics. He has made over 1000 arrests. Is it proper to write, “I have worked thirty-three (33) years in narcotics and made one-thousand (1000) arrests.” I’ve often seen numbers written out and then parenthetically clarified. Is this proper usage?

  • Dale A. Wood

    In German, the abbreviation “z.B.” includes the capital “B” because all nouns are capitalized in German. z.B. = “zum Beispiel”, and Beispiel is a noun.
    In the case of “Bundesrepublik Deutschland”, this is a proper noun. Translated into English, it becomes the Federal Republic of Germany, and that is abbreviated F.R.G. with all capitals because it represents a proper noun.

    Formerly, there was an awful place called the D.D.R., the “German Democratic Republic” in English, which was neither democratic nor a republic. That was as bad as the Holy Roman Empire, which was neither holy, nor Roman, nor an empire!

  • Dale A. Wood

    Concerning Steve Parker:
    “Also, I would rarely use full points in abbreviations”.
    That is just an oddity of British English that you ought to get rid of.

    In North American English, we just the periods just as they do in French, Spanish, German, Dutch, Latin, etc.:
    Mr., Mrs., Dr., Fr., a.m., p.m., e.g., etc., i.e., Hon., Jr., Sr., Sra., u.s.w., z.B.
    Notes: Dr. means “Doctor” in English, Spanish, or German. Also, in Spanish, there is “Dra.” for a doctor who happens to be a woman, and these abbreviations inclue dentists, professors, and so forth.
    Fr. is the abbreviation for “Father” – a Catholic priest.
    a.m., p.m., e.g., and i.e. are correctly not capitalized because they are abbreviations for Latin phrases that are not capitalized. For example: a.m. = “ante meridian”.
    Sr. means “senior” in English, but it means “Senor” in Spanish, with a tilde over the “n”. Sra. means “Senora” in Spanish.
    In German, u.s.w. means “und so weiter”, and that it the German for “and so forth”. This is used instead of etc.
    In German, z.B. means “zum Beispiel”, which means “for example”. This is used instead of e.g.
    Depending on the context, Sr. can also mean “Sister” in English – in other words, a Catholic nun like “Sr. Margaret Maples”.

    There really is something positive to say about something that is standard across many languages.

  • Dale A. Wood

    I agree with Venax completely:
    “Is the correct time 8:22 or 28:22?” Really cannot say.
    Really can say!! 28:22 is never the correct time anywhere on the planet Earth. There are only 24 hours here, so it’s never 28 o’clock. That’s not an English rule, just a natural one.
    The expression “28:22” was actually a mistyping of “20:22” (in the previous) comment, but that should have NEVER been allowed to happen. The “28:22” is a glaring error, and it should have been caught and corrected immediately. Days have exactly 24 hours in them, by definition.
    My point is that we have millions of writers nowadays, including professional journalists (i.e. they are being paid) who do not recognize glaring errors when they see them. Their skills at math, science, and logic are just that poor.
    I think that students aspiring to degrees in journalism should be required to pass courses in mathematics, chemistry, phyiscs, biology, and statistics. We live in a world of science and technology, and people who aspire to important positions ought to be required to learn the basics of these.

  • Dale A. Wood

    Venqax said: “Isn’t it about time that the USA moved on from imperial measurements to metric? We did, for scientific measures, which is the only place it makes sense.”

    In the United States, the metric system is used in pharmaceuticals, electricity, alcoholic beverages, and other such places. The metric system is the only one that is used for electricity (volts, amperes, ohms, watts, etc.) We electrical engineers know this!

    Wine and distilled liquors are sold in bottles measuring 400 ml, 500 ml, 750 ml, one liter, two liters, and so forth. There was an antique measurement in North America called “a fifth”. It was defined as one fifth of an American gallon. NOW, a fifth is defined as 750 ml exactly.

    Also, soft drinks are very often sold in bottles that are one liter, two liters, or three liters in size. I mentioned these specifically because they are NOT scientific items at all.

    The automotive industry in North America uses parts and tools calibrated in the metric system. This is extremely useful especially since parts and assemblies for cars and trucks are often make in one country but then assembled into complete vehicles in the other. For example, the General Motors Corporation exists in both countries, and it is very strong in Ontario in Canada, as well as in the Great Lakes states of the United States. There are also thousands of different subcontractors for vehicles. Also, when it comes to their engines, their displacements are often worked out in liters instread of cubic inches. For example, there are engines of 1.6, 2.0. 2.4, 3.0, 4.0 liters in displacement, et cetera. We all use the same size wrenches, etc., on our cars and trucks, all calibrated in metric sizes in millimeters.

    American and Canadian military, naval, and air force items designed and built on metric standards – especially to enhance cooperation with our European allies in NATO, and in the case of the United States, our allies in Australia, Japan, South Korea, South America, etc. Military and naval commanders measure distances in meters and kilometers, and many weapons systems have standard meausrements like 9.0 mm (pistols), 20 mm, 30 mm, 50 mm, 75 mm, 81mm, 90 mm, 105 mm, 155 mm, and 175 mm.
    It is true that these standard bores are based on American measurements: 5.56 mm (22 caliber), 7.62 mm (30 caliber), 12.7 mm (50 caliber), and 203 mm (six inches).

    Many of these standards date back a long way. The standards for artillery in the U.S. Army and Marine Corps were metric back during WW II. (The standard 75 mm bore for cannons was adopted from the French Army.) Also, early during WW II the U.S. Navy needed much-improved antiaircraft weapons – rapid-fire cannon. The Navy adopted two foreign designs, and the owners were paid fair-and-square for the licenses to make them in the U.S.A.: a 20 mm cannon from Oerlikon in Switzerland and a 40 mm cannon from Bofors in Sweden.

  • Dale A. Wood

    Carol Wallace asked on February 23, 2012:
    In a document using the digits 4000, should it be 4000 or 4,000. Is there a preferred useage? Thank you.

    According to the rules of the International System of Units (the S.I.), four-digit integers (i.e. the ones from 1000 to 9999) may be written with or without the comma or any other kind of a mark between the digits.

    Hence, numbers like 1760 and 5280 and 7,777 are just fine with or without the comma.

    Sometimes it just pays to use scientific sources for such things.

  • Sally Poulson

    When I did my PhD (in English literature), the style guide we adhered to insisted on ‘nineteenth-century novels’ (hyphenated, lower case when used adjectivally) but ‘novels in the Nineteenth Century’ (unhyphenated, upper case when used nominally). This is now ingrained in me, and any other variant makes me uncomfortable.

  • Tracey

    Interesting article. I didn’t know the rules varied. I just assumed numbers should all be written out. Good to know. Thanks for sharing.

    It’s true that writing techniques are an important art to master if you want your writing to be taken seriously.

  • Steve Parker

    When I started in journalism in the UK, we were taught “25 per cent” not “25 percent” (although percentage is of course one word). Presumably because “per” and “cent” are two words in Latin, in the same way as you would use “per annum” not “perannum”. Is this not the case in the USA?

    Also, I would rarely use full points in abbreviations – so, 10pm, not 10P.M.; Dr Smith not Dr. Smith; TV, not T.V.

    Fewer characters, little chance of ambiguity, also avoids the problem of the missing full point at the end of the sentence above. Exceptions are when it’s a proper noun, of course, when it’s up to the creator of the name.

  • venqax

    isn’t it about time that the USA moved on from imperial measurements to metric? We did, for scientific measures, which is the only place it makes sense. Why would you say someone is 183 cm, when you can say he’s six feet? Everyday measures are much better for everyday things. Why wouldn’t you say it’s 3 miles away when everyone knows what that means? A 200-pound man is a big man. 90 kgs? Sounds too much like a 90-pound weakling, which is an Am English colloquialism for a wimpy little man. Simply no reason to adopt metric outside the laboratory. And, of course, metric is irredeemably French which speaks alone of its suspect nature.

    A.m. and p.m. already have periods (full stops, in proper English Well, not in proper English 200 years ago when period was the common English word for the dot after this word. Once again, “the British” decided to change the language for some trendy slang, and then tried to pretend it was the august original. Sorry, old trick.

    In a legal document, what is proper: ten inch (10″) nails or ten (10) inch nails. That’s a question for legalese, not regular English. Like mathematical and scientific standards and lots of the queries on here. Specialized areas don’t use standard English grammar rules. Never have. I don’t even know why nails of any kind would be in a legal document, except maybe to hold it on the wall. Is it like “pricking” a sheriff’s writ?

    “3300″ is sometimes read (for what purpose I know not), “thirty three hundred”. Would that person read “330″ by saying, “thirty three tens”? No. They wouldn’t read eleven as one-teen or tenty-one, either. It’s called idiom and English is full of it (meaning it has many of them). Using hundred in such a context, e.g., “The Forty-Four Hundred” is very old, established usage in English (not in mathematics).

    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 You shouldn’t use it ever, unless you find yourself in 1889. Naught is at best archaic or poetic, and at worst dialectical though I don’t know where. Use the word “zero”. It means zero. Or use the word nothing. It means nothing. Point zero zero two. Or zero point zero zero two if there is some chance of confusion.

    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. It entirely depends on what kind of document you are writing. In contracts, e.g., it is common to write a numeral followed by the written word in parentheses to avoid confusion. “You have 3 (three) days to file your reply with proper grammar.”

    Irregardless of this rule telling you to spell it “6th Street”, if its name is “6th Street”, write it as “6th Street”. Except at the beginning of a sentence. Then you have to write Sixth Street, regardless. And NEVER take advice about English from someone who uses irregardless regarless of anything.

    I’d want to interpret “three hundred seven” as two numbers: 300 and 7. Why? That would not make sense. Would you interpret twenty-five as two numbers, 20 and 5? You wouldn’t say twenty and five, unless you were writing a poem. It’s exactly the opposite: One would interpret three-hundred seven as the number 307, and three-hundred and seven as two numbers, like calling lottery numbers. “300” followed by “7”.

    “out of the 24 cheques given 15 cheques were cashed”..i am sure this usage is not correct..please do tel me the correct usage. Certainly, “Out of the 24 checks given 15 checks were cashed.” BTW, you could write out twenty-four and fifteeen too, if you wanted to. Glad to help.

    Do I type “a” or “an” before the number 120? Why would you ever use “an” before 120? “An one-hundred and twenty”, “an hundred and twenty”. “An one two zero”. Any would be equally wrong.

    The most “mistakes” in writing come from the adaptations used in the “colonies”.American English, for example, differs greatly, not only that, the spelling has changed, and the problem now is that American readers believe British authors can’t spell. Arguably they can’t. If you take the position that the older is the better, in many cases it’s the British spelling that has changed and the American that has remained the same (what the British used to be, too). If you don’t want to accept that the 2 are separate dialects with distinct standards, then British has to justify at least as many alterations from the 17th, seventeenth, or XVII century as American does.

    Take the word “because”; the corect abbreviation is – cos’… In the USA, it is – cause In the USA cuz is often used in dialogue as short for because. Cause is not used as a short form of because.

    Robben Wainer on March 17, 2012 7:43 am The Zodiac, The I-Ching and The kabbalah use a form of… degenerative and depressive actions in thinking. Thank you for that, Robben Wainer. What board were you looking for?

    Is the correct time 8:22 or 28:22 ? Really cannot say. Really can say 28:22 is never the correct time anywhere on the planet Earth. There are only 24 hours here, so it’s never 28 o’clock. That’s not an English rule, just a natural one. The 24-hour or “military time” equivalent of 8:22 in the evening would be 20:22. Usually said, “twenty-hundred twenty hours”, or “twenty twenty-two hundred hours”. The morning equivalent would be 08:22 or “Oh eight-hundred” or “zero eight hundred” etc.

  • Rajesh Chaudhary

    How about when we write for the molecular lab procedure? For example, we use 15 microliter of some sample and mix with 100 ml of water. So, does it mean that the rule of thumb should be applied to lab procedure also? or to the recipe we make?

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