WSU Cougar Head Logo Washington State University


WSU Editorial Style Guide

Numbers below 10 are spelled out.

  • Exception: Percentages, semester hours, and grade point averages.
    • 10 percent, 3 semester hours, 3.5 grade point average (unless the number begins a sentence).
    • Enrollment increased by 25 percent. Twenty-five percent of the students were over the age of 20.
  • Exception: It is sometimes better to use numerals in ads, posters, and websites for ease of reading.
  • Treat numbers alike in a sentence if they refer to the same thing: “The class of 150 students was separated into smaller groups of 4 students each.”

Use “more than” rather than “over” with numerals.

  • “Enrollment is more than 18,000 students.”

Numbers at beginning of sentences

Always spell out numbers at the beginning of a sentence or reword the sentence to avoid spelling out a large number.

Ordinal numbers

Spell out ordinals in text.

  • first
  • second
  • tenth
  • Not 1st, 2nd, 3rd

When ordinal numbers are needed (as in rankings), do not use superscript letters.

  • “The program is ranked 16th in the nation” (not 16th).

Ordinals are never needed with months and days.

  • “On May 2, the program began” (not “On May 2nd”).

Numbers of four digits or larger

Use a comma for larger numbers.

  • 1,500
  • 35,000

Very large, round numbers should be expressed with a figure and word.

  • 450 million
  • $2 billion

Exceptions: Dates (1892), temperatures (-1200 degrees), and test scores

Decimals and fractions

List decimals and fractions in figures.

  • 1.25
  • 2/3

In some cases, a fraction may be spelled out.

  • “The professor covered about two-thirds of the chapter during the class.”
  • Note that hyphens are used when spelling out fractions.


Figures plus a.m. or p.m. (lowercase with periods) are used to designate time in both text and schedules.

In many informal contexts, a shortened form is fine. But in some cases, it’s better to use the full time. Readability and comprehension are the guiding factors.

  • “The lecture will begin at 10 a.m. with a luncheon to follow at noon.”
  • Meeting: 5 p.m.
  • The event will be held from 1:00 to 3:30 p.m.
  • Note that “noon” is lowercase and is not used with 12:00.
  • Very formal or ceremonial contexts may be best served by using a spelled-out format:
    Dinner will be served at six o’clock in the evening.

Plurals of numbers

List plurals by adding an “s.”

  • 5s
  • 20s
  • 1980s

Centuries and decades

Spell out centuries and decades where possible.

  • fifteenth century
  • the sixties

If using figures, they should have an “s” at the end.

  • 1960s
  • ’60s

Telephone numbers

Write telephone numbers with a hyphen after the area code.

  • 509-335-3518
  • Do not use a 1 to precede the area code: 800-335-3518

Numbers between -1 and 1

Use plural, not singular, for fractional numbers less than 1.

  • 0.4 miles, not 0.4 mile