Using Numbers and NumeralsWriter's Web
Amy Addison
(printable version here)

Special thanks to Hans Westerbeek, Tilburg University, The Netherlands, for alerting us to a needed update and a minor correction.

These general rules may assist writers struggling to be consistent when expressing numbers in writing. The first rule would be to consult a handbook for a specific field of study. There exist subtle differences between the formats for Modern Language Association, American Psychological Association, and Chicago Manual of Style.

Spell out as words:

  • Numbers that begin a sentence.
    • ex.: Three years ago I moved to Virginia.
  • Numbers that can be spelled out in one or two words.
    • ex.: ten, twenty, and eighty (a hyphenated number like thirty-six equals one word).
  • Numbers that are used as compound adjectives.
    • ex.: A twenty-mile hike.

Express as numerals:

  • Numbers that can not be written in one or two words.
    • ex.: 153, 2001, and 8,000,000.
  • Numbers representing dates, although the day of month may be written out if the year is not included.
    • ex.: July 4, 1776, December Seventh (or December 7).
  • Numbers in addresses.
  • Numbers expressing exact amounts: percentages, fractions, decimals, statistics, scores, or specific sums of money.
  • Numbers representing pages, acts, or scenes in plays and literature.
    • ex.: page 10, Act III, but "third scene," "part two" are also correct.
  • Numbers expressing time (except when followed by "o'clock").

Exceptions and additional rules:

  • It is acceptable to express a decade by spelling it out or writing it as a figure.
    • ex.: 1960's or sixties.
  • If a passage includes numbers that follow one another, one is spelled and the other is represented with a figure.
    • ex.: We used ten 2-gallon cans of red paint on the garage.
  • Be consistent! If you begin by expressing your percentages with figures, or spelling out your references to decades, make sure you continue to do the same thing for the rest of the project.

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