A. Write out numerals nine and under.
B. Use numbers for:
- Figures 10 or over, including ordinals, e.g., 22nd.
- Days of the month, omitting rd, th, st, nd.
- April 6, June 1
- Degrees, ratios, percentages, persons' ages.
- longitude 6°7'06"W
- 21.5°F below zero
- 6 percent
- 7 years old
- Dollars in all except casual references.
- The book cost $4.
- Dad, please give me a dollar.
- Apply appropriate guidelines (see No. 1) for items in a series.
- They had 10 dogs, six cats and 97 hamsters.
- Sums that are cumbersome to spell out, but spell out the word million.
- 17.9 million
- 3 million (note use of digit, since 3,000,000 is being represented)
- Write phone numbers with the area code set off by a hyphen, e.g., 800-555-1212.
- Use extended ZIP codes wherever possible.
C. Avoid Unnecessary Ciphers
- Hours of the day: 7 p.m., 7:30 p.m., noon, midnight. Do not put 12 in front of noon or midnight. Do not say 7 p.m. tonight. Do not use 7:00 except in lists of events, etc., to preserve alignment of type.
- In amounts of money with the dollar sign: $3 (not $3.00), unless tabulated in columns.
- Do not begin a sentence with numerals; supply a word or spell out the figures. Please note that numbers below 100 should be hyphenated when they consist of two words.
- Do not add a numeral in parentheses after it's written in words:
- three copies, not three (3) copies