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Numbers in APA Style (7th ed.)

The American Psychological Association’s (2020) Publication Manual of the American Psychological Association provides extensive information and examples on using numbers. This FAQ will focus on the basics, so please refer to the manual for more information.

A. General rule: “Use numerals to express numbers 10 and above and words to express numbers below 10” (American Psychological Association [APA], 2020, p. 178).

B. Use numerals to express numbers that

  •  “immediately precede a unit of measurement” (APA, 2020, p. 178) e.g., 2 cm.
  • “represent statistical or mathematical functions, fractional or decimal quantities, percentages, ratios, and percentiles and quartiles” (APA, 2020, p. 178) e.g., divided by 4, more than 2%.
  • “represent time, dates, ages, scores and points on a scale, exact sums of money, and numerals as numerals” (APA, 2020, p. 178).
  •  “denote a specific place in a numbered series, parts of books and tables, and each number in a list of four or more numbers” (APA, 2020, p. 178).

C. Use words to express

  • “any number that begins a sentence, title or text heading. (Whenever possible, reword the sentence to avoid beginning with a number)” (APA, 2020, p. 179).
  • “common fractions” (APA, 2020, p. 179) e.g., one third of the group.
  • “universally accepted usage” (APA, 2020, p. 179) e.g., the Ten Commandments

D. Use words and numerals to express “back-to-back modifiers” (APA, 2020, p. 179) e.g., 2 four-way stops.

  • Exception: If readability suffers, spell out both numbers e.g., “first two items”, not “1st two items”  or “first 2 items”.

E. “Use commas between groups of three digits in most figures of 1,000 or more” (APA, 2020, p. 180).

Exceptions:

  • page numbers e.g., page 1029
  • binary digits e.g., 00110010
  • serial numbers e.g., 290466960
  • degrees of temperature e.g., 3071 F°
  • acoustic frequency designations  e.g., 2000 Hz
  • degrees of freedom  e.g., F(24, 1000). (APA, 2020, p. 180)

F. “To form the plurals of numbers . . . add s or es alone, without an apostrophe” (APA, 2020, p. 181) e.g., 1800s, sixes and sevens.

For more information on numbers, including more details on the information provided here as well as how to present ordinal numbers, decimal fractions, and Roman numerals, please see pages 178-181 in the APA Style manual and Numbers on the APA Style website.

If you have questions about this writing tip or any other writing matter, please contact the Writing Centre.

Theresa Bell
Manager, Blended Learning Success

(Originally published in Crossroads April 20, 2016; updated with APA Style (7th ed.) information September 16, 2020)

Reference

American Psychological Association. (2020). Publication manual of the American Psychological Association (7th ed.). https://doi.org/10.1037/0000165-000​