When are numbers expressed in words?

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.

Examples:

  • Ten participants answered the questionnaire.
  • Forty-eight percent of the sample showed an increase; 2% showed no change.

common fractions

Examples:

  • one fifth of the class
  • two-thirds majority

universally accepted usage

Examples:

  • the Twelve Apostles
  • Five Pillars of Islam

(adapted from the sixth edition of the APA Publication Manual, © 2010)