Using Numbers and Numerals

Amy Addison, UR Writing Center Tutor (WC '93)

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.: 1960s 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 all the way through your paper!