Lowercase, spelling out numbers less than 10: the first century, the 21st century. For proper names, follow the organization’s practice: 20th Century Fox, Twentieth Century Fund, Twentieth Century Limited.
Use numerals to show fractions.
5 1/2, not “five and one-half”
75 3/4, not “75 and three-fourths”
Capitalize the names of months in all uses. When a month is used with a specific date, abbreviate only Jan., Feb., Aug., Sept., Oct., Nov., Dec. Spell out when using alone, or with a year alone.
Fall semester classes will start on Aug. 28, 2017.
December is the busiest month for shopping.
The photo was taken in July 2013.
Spell out numbers one through nine and any number that begins a sentence.
John took six courses during fall semester.
Seventy people showed up for the seminar.
There are 12 months in the year.
numerals of 1,000 and above
Use commas in the appropriate places, except for temperatures and years.
RIT has more than 18,000 students.
The boiling point of uranium is 3818°C.
She plans to retire in 2020.
One word. Use numerals when referring to percentages, unless the number is the first word of the sentence; then spell out the number. Repeat percent with each individual figure.
There will be a 7 percent increase in tuition this year.
Seventy-five percent of RIT’s students live on campus.
He said 10 percent to 30 percent of the electorate may not vote.
Use figures. Use hyphens between sections of the number, not periods. Do not use parentheses around the area codes. The form is 212-621-1500. For international numbers use 011 (from the United States), the country code, the city code, and the telephone number: 011-44-20-7535-1515. The form for toll-free numbers is 800-111-1000. If extension numbers are needed, use a comma to separate the main number from the extension: 212-621-1500, ext. 2.
Use figures except for noon and midnight. Use a colon to separate hours from minutes:
There is no space on either side of the hyphen in time spans.
7:30 a.m.-9 p.m.
When using a.m. or p.m., always lowercase, with periods.
Avoid such redundancies as 10 a.m. this morning, 10 p.m. tonight, or 10 p.m. Monday night. Use 10 a.m. today, 10 p.m. today, or 10 p.m. Monday.
The construction 4 o’clock is acceptable, but time listings with a.m. or p.m. are preferred.
Spell out: 50 hours, 23 minutes, 14 seconds. When using the abbreviated form, as in sports statistics or similar agate use, or subsequent references, the form is 2:30:21.65 [hours, minutes, seconds, tenths, hundredths].
Use figures, without commas: 2017. Use commas only with a month and day: Oct. 11, 2016, was a special day. Years are the lone exception to the rule against using numerals to start a sentence. When denoting class years, it is acceptable to use an apostrophe in place of the numerals denoting century: Joe Smith ’16; John Doe ’09. Make sure the apostrophe is facing the correct way.