This page is part of our Editorial Style Guide.
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For all numbers, use the Chicago 9.3 alternative rule: spell out single-digit numbers and use numerals for all others except:
- use numerals in tabular data
- use numerals when used with the word “percent.” (See Percentages.)
CORRECT: Olivia Creasey took second place in the 2019 Grad Slam.
INCORRECT: Olivia Creasey took 2nd place in the 2019 Grad Slam.
Do not use superscript for ordinal numbers.
CORRECT: The department was ranked 12th in the nation.
INCORRECT: The department was ranked 12th in the nation.
When to spell out the range: This depends on context and the sound of the sentence. There will be times when spelling out a range is more appropriate, and aids in understanding of complex ideas, for example:
CORRECT: The researchers found that in from 40 to 60 percent of the six-to-eight-cell microtissues assembled with a single abnormal cell …
INCORRECT: 40-60 percent
INCORRECT: 6-8 cell microtissues
Use cardinal numbers for dates; do not use ordinal numbers.
CORRECT: The ceremony will be held on November 14.
INCORRECT: The ceremony will be held on November 14th.
Follow Chicago 9.18: “In nontechnical contexts, the word percent is generally used; in scientific and statistical copy, the symbol % is more common.”
Use numerals with the word percent in most cases, except at beginning of a sentence.
EXCEPTION: if the text is dense with percentages (e.g., a detailed research story), or for charts and tables, the % symbol is preferred.
CORRECT: Only 7 percent of the students replied to the alumni survey. Sixteen percent requested removal from the email list.
CORRECT: Sixty percent of subjects had full remission, 31.2% had partial remission, and 8% had no response to the treatment (0.8% left the study).
For a range of percentages:
CORRECT: an approval rating of 40 to 50 percent
CORRECT: an approval rating of 40% to 50%
INCORRECT: an approval rating of 40 percent to 50 percent
INCORRECT: an approval rating of 40-50 percent.
CORRECT: 415-476-2577 (included as an option in UCSF Style)
INCORRECT: 415.476.2577 and (415) 476-2577 and 415/476-2577
Next topic: Punctuation and Spelling