Above or below 10
6.1. Spell out whole numbers below 10. Use numerals for 10 and above.

• Right: They performed two experiments.
• Wrong: They performed 2 experiments.
• Right: They performed 11 experiments.
• Wrong: They performed eleven experiments.

6.2. Spell out numbers in casual expressions:

• Right: He must have done the experiment a hundred times.
• Wrong: He must have done the experiment a 100 times.
• Right: She walked a half-mile to class.
• Wrong: She walked a ½ mile to class.

In tables, charts and graphs
6.3. Always use numerals (1, 2, 3...14, 15...)

In proper names
6.4. Use words or numerals according to an organization's practice.

• Right: 20th Century Fox
• Wrong: Twentieth Century Fox
• Right: Twentieth Century Fund
• Wrong: 20th Century Fund

Percent
In text
6.5. Always spell out "percent."

• Right: About 14 percent of the class attended the lecture.
• Wrong: About 14 % of the class attended the lecture.

6.6. Use numerals with "percent," even if the number is less than 10.

• Right: About 4 percent of the class attended the lecture.
• Wrong: About four percent of the class attended the lecture.

In tables, charts and graphs
6.7. Use the percent (%) sign.

Dates
In text
6.8. Spell out the names of months.

• Right: Classes started on September 10.
• Wrong: Classes started on Sept. 10.

In tables, charts and graphs
6.9. Abbreviate months, except for May, June and July. MEMORY TIP: The three months in question have four or fewer letters.

6.9. It is acceptable to use numeral dates with slashes.

• Right: 2/3/02 (February 3, 2002)
• Wrong: 02/03/02
• Wrong: 2-3-02
• Wrong: 02-03-02

Ordinals
6.10. Do not use ordinal numbers in dates.

• Right: January 9, 2002
• Wrong: January 9th, 2002

Comma
6.11. Use a comma when two numbers are adjacent in a date.

• Right: January 2, 2002
• Wrong: January 2 2002
• Right: 2 January 2002
• Wrong: 2, January 2002
• Right: January 2002
• Wrong: January, 2002

Time
Noon and midnight
6.12. Use "noon" and "midnight" rather than "12 p.m." and "12 a.m.," respectively.

• Right: The class ended at noon.
• Wrong: The call ended at 12 p.m.

Hours and minutes
6.13. If a time is a precise hour, do not indicate minutes.

• Right: The time was 6 p.m.
• Wrong: The time was 6:00 p.m.
• Right: The time was 6:30 p.m.
• NOTE: "a.m." and "p.m." are lower case and use periods; there is a space separating them from the numbers.

Redundancy
6.14. Avoid redundancy.

• Right: It was 9 a.m.
• Wrong: It was 9 a.m. in the morning.
• Right: It was noon.
• Wrong: It was 12 noon.