UCSF

Numbers

This page is part of our Editorial Style Guide.

On this page

Overview

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.)

Do say: Olivia Creasey took second place in the 2019 Grad Slam.

Do not say: Olivia Creasey took 2nd place in the 2019 Grad Slam.

Do not use superscript for ordinal numbers.

Do say: The department was ranked 12th in the nation.

Do not say: The department was ranked 12th in the nation.

Numbers in a range

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:

Do say: The researchers found that in from 40 to 60 percent of the six-to-eight-cell microtissues assembled with a single abnormal cell …

Do not say: 40-60 percent

Do not say: 6-8 cell microtissues

Dates

Use cardinal numbers for dates; do not use ordinal numbers.

Do say: The ceremony will be held on November 14.

Do not say: The ceremony will be held on November 14th.

Times

Do use a.m. and p.m. which follows Chicago 9.37 and 10.41 and UCSF Style.

Do not use all-numeric dates, e.g., say July 1, 2025 instead of 7/1/2025. This follows Chicago 9.35.

Percentages

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.

Do say: Only 7 percent of the students replied to the alumni survey. Sixteen percent requested removal from the email list.

Do say: 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:

Do say: an approval rating of 40 to 50 percent

Do say: an approval rating of 40% to 50%

Do not say: an approval rating of 40 percent to 50 percent

Do not say: an approval rating of 40-50 percent.

Phone numbers

Do say: 415-476-2577 (included as an option in UCSF Style)

Do not say: 415.476.2577 and (415) 476-2577 and 415/476-2577

Next topic: Punctuation and Spelling