Use numerals to express:
a. numbers 10 and above
examples: 12 years old, the 57th trial, 12 cm wide
b. numbers that precede a unit of measurement
examples: 5-mg dose, 36.3 mm
c. numbers that represent statistical or mathematical functions, fractional or decimal quantities, percentages, and ratios
examples: multipled by 5, .33 of the..., more than 5% of the sample..., a ratio of 15:1
d. numbers that represent time, dates, ages, scores, points on a scale, exact sums of money and numerals
examples: 1 hr 34 min., at 3:45 am, 2-year olds, score 5 on a 12 point scale
Use numbers expressed as words:
a. when the number begins a sentence, title, or heading
examples: Forty-eight percent of the sample..., Twelve students improved...
b. common fractions
examples: one fifth of the class..., two-thirds majority
c. universally accepted language
examples: the Twelve Apostles, Five Pillars of Islam
For more information, see the Publication Manual of the American Psychological Association. You might also find help using the APA Style blog.
Q: Sometimes I see numbers spelled out (nine) and at other times I see them in numeric form (9). Which is correct? When do I spell out numbers and when do I write them out? —Kevin T.
A: Most writers—including me—took on this artistic profession for three reasons: We’re creative, we love to read and, most important, we want to avoid numbers at all costs. Yet somehow, even in writing, numbers have found a way to sneak back into our lives.
There are several rules of thought on how to handle writing numbers, but the most common is pretty simple. Spell out numbers under 10 (zero through nine), and use the numeric symbols for numbers 10 and up. I bought eight candy bars from the vending machine. I average eating 29 candy bars per month.
There are some exceptions to the rule. For example, spell out all numbers that begin a sentence. Forty-seven-thousand contestants were turned down for “American Idol.”Eleven were selected. Of course, there’s an exception to the exception: Don’t spell out calendar years, even at the front end of a sentence. 1997 was the year I met my wife. And, if you don’t feel like writing those long, awkward-looking numbers, just recast the sentence. American Idol turned down 47,000 contestants. I met my wife in the magical year of 1997.
Also, there are other instances where the under-10/over-10 rule doesn’t apply. Always use figures for ages of people (“He’s 9 years old”), dates (February 14), monetary amounts ($8), percentages (14 percent) and ratios (2-to-1).
Again, this is a style issue and other sources may suggest different ways of handling numbers. So please, no hate mail. And let’s agree not to talk about numbers for the rest of the day—they make my head hurt.
Check out these Grammar Rules to help you write better:
Sneaked vs. Snuck
Who vs. Whom
Lay vs. Lie vs. Laid
Which vs. That
Since vs. Because
Ensure vs. Insure
Home in vs. Hone in
Leaped vs. Leapt
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Brian A. Klems is the editor of this blog, online editor of Writer’s Digest and author of the popular gift bookOh Boy, You’re Having a Girl: A Dad’s Survival Guide to Raising Daughters.
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