Numerals

Spelling Out
Spell out the numbers one through nine, including the ordinal form (first, ninth), except for GPA, credit hours, percentages, decimals, book sections and pages, or when the number is part of the official term, such as 7th Fleet.

She has a 4.00 GPA.
He is taking 6 credit hours this semester.
That's 5% more than it was last week.
See Chapter 3, page 7 for the answer.
He is the third professor so honored.

Use figures in a range or series where at least one of the numbers is more than two digits (an eight-week program, butan 8- to 12-week period). Do not use both a figure and a word to indicate one number. (He had three (3) classes.)

Adjacent Numbers
When two numbers are adjacent to each other in a sentence, use a combination of a numeral and a spelled-out number. If one of the numbers is a unit of measurement, keep that as a numeral. (We had sixteen 4-foot boards.) Otherwise, spell out the shorter of the two numbers. (The copy center reproduced 750 eight-page workbooks.)

Beginning a Sentence
Spell out a number that begins a sentence, except if that number is a year. (1976 was the nation's bicentennial. Thirty-six students attended.)
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Dates

Use the cardinal number in dates: The party is March 3 (not March 3rd), and do not use on if it can be avoided. Do not use a comma in dates that include only the month and year (January 2002). If giving the month, day and year, the year is set off with commas. (September 11, 2001, is a day all of us will remember.)

When writing out a date like July 4, it is always "July 4," not July 4th. Is there an instance where 4th can be used when referring to the date? Yes, the "4th of July" or "fourth of July" is correct because you are placing it in a series of all the days in July.

Footnote Numbers
Asterisks and superscripts follow punctuations marks (except dashes) in text and are placed outside the closing parenthesis.

Fractions
Spell out and hyphenate fractions that are less than one. (Two-thirds of the class passed.) Use figures for fractions greater than one (2 3/16).

Inclusive Numbers
Inclusive numbers that are represented by a beginning and ending number (e.g., page numbers, duration) can be joined by a dash (1990-98) or related by a pair of prepositions (from 1996 through 1999). Do not mix the two forms; in other words, do not use from 1996-99.

Large Figures
For numbers of four or more digits, include a comma (1,530; 27,500). Exceptions are SAT scores, page numbers, years and temperatures. Very large figures can be expressed with a figure and a word (352 million, 13 billion).

Money
For even sums of money, delete the .00 unless the figure is aligned in a table with other figures that include cents, or if the even figure is used in the same context with fractional amounts. (The tickets were $15.00, $12.50, $10.00 and $7.50.)

For even amounts of $1 million or more, use the dollar sign and million or billion ($6.2 million, $3 billion). For amounts under one dollar, use the word cents; do not use the dollar sign or decimal point (35 cents).

Percent
Use the symbol % when it accompanies a number. (A 2019 AP Stylebook change)

Phone Numbers
Use figures. The form: 212-621-1500. For international numbers, use 011 (from the U.S.), the country code, the city code and the telephone number: 011-44-20-7535-1515. Use hyphens, not periods.
Form for toll-free numbers: 800-111-1000.

If extension numbers are needed, use a comma to separate the main number from the extension: 212-621-1500, ext. 2.

Time
Except for schedules or agendas, use 2 p.m. rather than 2:00 p.m. (Example: We will meet at 1 p.m. to discuss the program.) 

However, if any of the times include minutes (e.g., 2:15 p.m.), include minutes for all times. (Example: The first meeting was scheduled at 3:15 p.m. and the second at 4:00 p.m.)  

To indicate a span of time, write from 2:15 to 2:45 p.m., not from 2:15-2:45 p.m.

Use "noon" rather than "12 p.m."