Whether to spell out numbers or use numerals is a matter of two things: context and style preference. Today, I highlight some things to consider when including numbers in your work. For clarity, in this post, words means spelling out numbers, as in four or nine, and numerals means using the numeric form (figures), like 4 or 9. Money, dates, and times are not covered here, even if some of the ideas can be equally applied.
General Guidelines and Disagreements
The Chicago Manual of Style (2017, 544) and Oxford’s New Hart’s Rules (2014, 186) give similar recommendations for nontechnical writing: Chicago spells out zero through one hundred, along with round multiples such as two hundred and thirty thousand, while Oxford spells out zero through ninety-nine and uses the numeral 100. Honestly, it seems like an odd difference given how closely the two align on this rule. They both say that a mixture of numerals and words is acceptable for large rounded values, such as 3 million and 1.5 billion, but both also accept words only; however, Chicago (2017, 545) explicitly states a preference for spelling out, as in three million and one and a half billion.
Walsh (2000, 176) recognizes what he calls “newspaper style,” which is spelling out values from zero through nine and using numerals for values ten and higher. I suppose the moniker “newspaper style” comes from the Associated Press Stylebook (2020, 212) and The Economist Style Guide (2018, 50) recommending roughly the same rule; however, The Economist recommends using numerals for values eleven and higher. Interestingly enough, Garner (2003, 560), who is not associated with newspapers, also has the same recommendation as The Economist. And the American Psychological Association (2020, 178) uses the same zero-through-nine threshold as the Associated Press, though with several exceptions for values below ten.
Sabin (2010, 138) is a bit more flexible, describing both a “figure style” (numerals), which he treats as the norm for most business writing, and a “word style” (words) for more formal writing. He pretty much says to be prepared to adjust your style as needed, and he gives plenty of examples of both styles (Sabin 2010, 138–41).
The general guidelines extend to ordinal numbers to a certain extent, so preference is for first, second, third, etc. rather than 1st, 2nd, 3rd, etc. But the so-called newspaper style would recommend 21st over twenty-first; the latter would be a Chicago and Oxford leaning. Chicago (2017, 546) also has a note to avoid the common legal style as in 122d or 123d, preferring 122nd and 123rd while also emphasizing that superscripts should be avoided.
Does Anyone Agree with Anything?
The guidelines for using words and numerals may seem quite disjointed and incongruent, and that is because they are. However, agreement can be had under certain circumstances. With abbreviated units of measure, numerals are preferred (Associated Press Stylebook 2020, 212–15; Chicago Manual of Style 2017, 549; Garner 2003, 560; New Hart’s Rules 2014, 193; Sabin 2010, 152; Economist Style Guide 2018, 50), so 10 m and 30° are quite proper wherever a guide allows the abbreviation or symbol. AP generally spells out the unit instead, as in 10 meters and 30 degrees. When the unit is spelled out in nontechnical writing, however, Chicago applies its general rule, as in twenty-six miles (2017, 549). Numerals are also standard for expressing exact numbers such as 1.03 and 0.5.
While there is uniformity on some things, the percent (per cent) symbol % is a bit of a sticking point. Everyone agrees on using numerals with percentages; however, whether to use the symbol or spell out percent (per cent) is an area of contention. Chicago (2017, 551), New Hart’s Rules (2014, 193), and Sabin (2010, 159) recommend spelling out percent (per cent) except in tables and statistical or technical contexts. The Associated Press Stylebook (2020, 213) and The Economist Style Guide (2018, 50) have a blanket recommendation for the symbol; Garner (2003, 560) says that either is fine. All of these manuals agree that, when using the symbol, no space should be between the numeral and the symbol, for example 5%; however, when spelling out percent (per cent), there is a space between, so 5 percent and 5 per cent are equally correct, depending on how one spells percent (per cent).
Thou Shalt Not Start with a Numeral
Here is a shocker: the style manuals and books colsulted for this post agree that sentences shouldn’t start with a numeral. More unity—almost. The Associated Press Stylebook (2020, 212–15) makes one exception: a sentence can start with a numeral that identifies a year, as in 1976 was a very good year. So, if you find yourself with a sentence like 122 people attended the conference, consider recasting it. Some examples could be In all, 122 people attended the conference or, if exact numbers are not important, Around 120 people attended the conference. Spelling out the number is also an option, as in One hundred twenty-two people attended the conference. (Not including and after hundred is Chicago style; New Hart’s Rules does not have a rule on this but does include and in some examples.)
Mixing Things Up in the Name of Consistency and Flexibility
Chicago (2017, 546) and New Hart’s Rules (2014, 187) agree that when several numbers occur in a sentence, a paragraph, or a closely connected series of paragraphs, consistency is important. So, it may be important to go against the general guidelines mentioned above. For example, in a sentence where there are figures like 5, 9, and 231, numerals are preferred even for the sub-one-hundred values.
The event started slowly. Within the first hour, just five people were in attendance; the next hour, nine; but by the third, 231. ❌ Not recommended.
The event started slowly. Within the first hour, just 5 people were in attendance; the next hour, 9; but by the third, 231. ✅ Recommended.
In the recommended example, notice how the ordinal numbers follow the general rule, but the cardinal numbers—5, 9, and 231—appear as numerals because they count the same thing in a single series. Mixing words and numerals can also help readers tell two numbers apart when they appear side by side, as in “thirty 10-page pamphlets or nine 6-room flats” (New Hart’s Rules 2014, 187).
Conclusion
Numbers are a big topic. Chicago, for example, has around twenty-five pages dedicated to it. Take care and be well.
References
American Psychological Association. 2020. Publication Manual of the American Psychological Association. 7th ed. Washington, DC: American Psychological Association.
The Associated Press Stylebook 2020–2022. 2020. 55th ed. New York: Basic Books.
The Chicago Manual of Style. 2017. 17th ed. Chicago: University of Chicago Press.
The Economist Style Guide. 2018. 12th ed. London: Profile Books.
Garner, Bryan A. 2003. Garner’s Modern American Usage. 3rd ed. New York: Oxford University Press.
New Hart’s Rules: The Oxford Style Guide. 2014. 2nd ed. Oxford: Oxford University Press.
Sabin, William A. 2010. The Gregg Reference Manual: A Manual of Style, Grammar, Usage, and Formatting. 11th ed., Tribute ed. New York: McGraw-Hill.
Walsh, Bill. 2000. Lapsing into a Comma: A Curmudgeon’s Guide to the Many Things That Can Go Wrong in Print—and How to Avoid Them. New York: McGraw-Hill.