Follow AP style. Spell out numbers up to and including nine, and use figures for 10 and above:
- one, eight, nine
- 10, 21, 105, 2,436
Number usage can be mixed in the same sentence or paragraph:
- Two administrators and 11 faculty members from UC Santa gave reports. Eleven journalists, three legislators, and 146 community members voiced their opinions.
Use the same rules for ordinal numbers:
- second, ninth, 10th, 25th, 169th
- UCSC’s five tennis players ranked first, third, 10th, l6th, and 23rd in the men’s singles competition.
Spell out numbers that begin a sentence or the title of a course. Spell out numbers one through nine if they occur with “century,” and use figures for 10 and above. In these cases, also spell out the numeral if it appears at the beginning of the sentence or course title:
- Twentieth-Century Chinese Art
- French History: The 19th Century
- Classical Chinese Culture and Literature: Sixth Century through 16th Century
- Professor Nicole Paiement specializes in 20th-century French music.
- Twentieth-century African American culture is Professor Tricia Rose’s field.
Use figures for course numbers, course credits or units, page numbers, scores, percentages, compound numbers, decimal fractions, and very large numbers:
- Biology 3
- 5-credit course
- page 7
- 5 percent
- 4 feet 7 inches
- $5 billion
- 3 million years ago