A concise list of Associated Press rules regarding numbers.
NUMERALS
In most cases, spell out whole numbers below 10 and use figures for 10 and above. Samuel bought two apples, one mango and 12 peaches. Spell out the number if it at the start of a sentence. Twenty thousand people attended the festival. Spell out the number in a casual expression; I told you a thousand times not to exaggerate.
AGE
For ages, always use figures. If the age is used as an adjective or a pronoun, hyphenate. The girl, 8, has a brother, 11. The student is 16 years old. A 16-year-old student. The training is for 16-year-olds. Don’t use hyphens when stating an age range. He is in his 40s.
DECIMAL UNITS
Decimals should not exceed two places in most content. An exception is blood alcohol content which is expressed in three decimal places. Precede amounts less than one with a zero. The stepladder is 0.62 meter tall.
FRACTIONS
Spell out fractions less than 1, using hyphens between the words. Two-thirds, three-quarters, one-half, and so on.
Use figures for precise amounts larger than 1. Convert to decimals whenever practical. For tabular content, use figures exclusively.
MONEY
Use the dollar sign and decimal point only for uneven dollar amounts. For example, $2.50, $3.15 and $5. It’s not $5.00.
For amounts less than one dollar, use the word “cents”, not “¢”. That costs 45 cents. This originated from the time when a cents symbol was not available on all typewriters. Use exact figures up to $1 million. For amounts over $1 million, write $1 million, $4.8 million, $1.15 billion.
ORDINALS
Ordinals are numbers used to indicate order. Spell out the first through the ninth. Use digits starting with 10th. First, second, 10th, 25th, and so on. Do not use ordinal numbers in dates. June 12, not June 12th.
PERCENTAGES
AP style recommends the use of numerals with “percent”, not “%”.
ROMAN NUMERALS
Use sparingly. They may be used for wars and to establish personal sequence for people and animals. World War II, King Henry VIII, Native Dancer II (a racehorse). Pro football Super Bowls are referenced by Roman numeral. For example, the 2018 Super Bowl was called Super Bowl LII.
TIME
Use lower case and periods for a.m. and p.m. If it is right on the hour, use just the hour digit. 3 p.m., not 3:00 p.m. Spell out noon and midnight. Do not use 12 midnight or 12 a.m.
TITLES and NAMES
Retain commonly known presentation. 4G phone, 101st Battalion, B-2 bomber, Apollo 9.
ZERO, NAUGHT, GOOSE EGG
Zero is spelled out wherever it can be confused with the letter O. The temperature was zero this morning.