Whole Numbers
Zero to nine
In almost all cases, write out numbers from zero to nine in letters. However, exceptions outlined in other sections of the Style Guide take precedence over this rule.
Examples
Correct:
She had eight sisters. Her oldest sister was born at 4 p.m. on March 5. Her oldest sister's hobby is constructing 1:8 figurines.
He spent a lot of money outfitting his level 99 swordmaster in the game, indifferent to the fact that the character was essentially a series of 0s and 1s stored on his computer.
Incorrect:
She had 8 sisters. Her oldest sister was born at four p.m. on March five. Her oldest sister's hobby is constructing one:eight figurines.
He spent a lot of money outfitting his level ninety-nine swordmaster in the game, indifferent to the fact that the character was essentially a series of zeros and ones stored on his computer.
10+
Write 10 and above in numerical form when they do not start a sentence, unless specified otherwise below.
Examples
Correct: He had 29 cousins.
Incorrect: He had twenty-nine cousins.
Sentence starters
Spell out numbers which begin a sentence (except for years). When you spell out compound numbers from 21 to 99, hyphenate them.
Examples
Correct: Twenty-nine cousins attended the wedding.
Incorrect:
29 cousins attended the wedding.
Twenty nine cousins attended the wedding.
Large numbers
Large round numbers (i.e. numbers which end in zero and are greater than or equal to one hundred) should be expressed as concisely as possible, usually either in words or with a combination of words and numbers. Large round numbers which can be written using three words or less should be written entirely using words. Additionally, fractional quantities in the millions or more should be written using a mixture of numbers and words, as below. If the two preceding cases do not apply, express the number without words.
Examples
Correct: two million, twenty-seven hundred, 2.1 million, 2,659,340
Incorrect: 2,000,000, 2,700, two million one hundred thousand, two million six hundred fifty-nine thousand three hundred forty
Essentially, express the number in the most sensible way possible.
Do not hyphenate large round numbers (except for compound numbers from 21 to 99), and do not use the word and when writing out numbers with three or more digits.
Examples
Correct: two million, twenty-two million, one thousand forty
Incorrect: two-million, twenty two million, one thousand and forty
4+ digit numbers
For numbers of four or more digits, use commas to separate every three digits to the left of the decimal point.
Examples
Correct: 138,259,501
Incorrect: 138.259.501, 138259501
See also
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