Numbers and Dates

Numbers

Spell out whole numbers up to (and including) one hundred (e.g., zero, one, ten, ninety-six) and use numerals for greater numbers (104, 1001, etc.) However, if there are many numbers referring to the same thing or several numbers in the same sentence, and some are over one hundred, use numerals for consistency. Never start a sentence with a numeral. If the author wrote, “101 dogs” either re-write (“The dogs numbered 101”) or spell it out (“One hundred one dogs”).

Percentages: always use numerals, never use the symbol: 1 percent. 99 percent.

Spell out whole numbers up to (and including) twenty when followed by hundred, thousand, hundred thousand, million, billion, and so on (e.g., eight hundred, 12,908, three hundred thousand, 27 trillion).

For ages: hyphenation is as follows:

• a three-year-old [hyphenate compound noun!]

• a five-year-old child [hyphenate compound adjective]

• a fifty-five-year-old woman

• a group of eight- to ten-year-olds

but

seven years old

Dates

We do not use the Chicago style for dates, preferring to write May 1, 2013, not 1 May 2019.

Decades and years

The seventies, eighties, not the '70s, '80s. Or, the 1970s and 1980s, not 1970s and '80s. Occasionally, you could say the class of '84 or the events of '68, but otherwise, use a more formal style. There is no apostrophe with years: 1940s.

April 18, not April 18th.

Always spell out a date at the beginning of a sentence: “Eighteen forty eight was a year of revolution, and many thought 1968 would follow it.” Rephrase if it seems awkward: ‘The year 1848 was one of revolution, and many thought. . .”