Cardinal and ordinal numbers from one to ninety-nine, such numbers followed by hundred, any number at the beginning of a sentence, and common fractions are spelled out. Fractions are hyphenated as well.
no fewer than six of the eight victims
no more than fifty-two hundred gallons
One hundred eighty-seven people were put to death there during the twenty-third century BC
at least two-thirds of the electorate
fully 38,000 citizens [use commas for numbers of four or more digits, except, of course, for years]
Numbers applicable to the same category, however, are treated alike in the same context.
no fewer than 6 of the 113 victims
Almost twice as many people voted Republican in the 115th precinct as in the 23rd.
Numbers that express decimal quantities, dollar amounts, and percentages are written as figures.
an average of 2.6 years
more than $56, or 8 percent of the petty cash
a decline of $.30 per share
Note that in humanistic texts, the word “percent” is written out, but the number is in Arabic rather than spelled out:
40 to 50 percent of the prisoners
British currency is abbreviated as follows:
₤106 4s. 6d.
Inclusive numbers follow the Booth-Reverand protocol, because it’s simpler than CMS 15 with its nine separate rules: always give the last two digits; if more than the last two digits change, then give the entire number:
1-13, 74-75, 100-10, 324-33, 397-403, 1462-78, 1462-1503.
Exception: when inclusive years appear in titles, give all four digits, i.e., 1789-1791.
Roman numerals are used in the pagination of preliminary matter in books, in family names and the names of monarchs and other leaders in a succession, in the names of world wars, and in statutory titles. They are also used for the traditional division of Acts and scenes: III.ii.136-37.
On page iii Bentsen sets out his agenda.
Neither John D. Rockefeller IV, Elizabeth II, nor John Paul II was born before World War I.
Yet Title XII was meant to rectify not only inequities but iniquities.
Arabic numerals are used for the parts of books.
In part 2, chapter 2, of volume 11 of the Collected Works, our assumptions are overturned.
See also Dates.