Numbers, dates, and time

Numbers

General rule: Spell out whole numbers from zero through one hundred (for example, three, ten, and eighty-five). Also spell out whole numbers from one through one hundred when they are followed by hundred, thousand, or hundred thousand (for example, one hundred thousand). Otherwise, use numerals. For more detail, see section 9.2 of The Chicago Manual of Style.

Examples:

• Thirty-two children from eleven schools joined our art workshop.
• According to recent research, this painting is 103 years old.
• The three new parking lots will provide space for one thousand more cars.
• Our weekly visitor count now stands at 5,893.

Centuries: When you refer to a specific century, spell it out in lowercase: "twentieth century," not "20th century," "20th Century," or "Twentieth Century." Hyphenate when used as an adjective, but not when used as a noun: “He believes that twentieth-century technology should stay in the twentieth century.”

Exception: Use numerals when providing an approximate date for a collection object: 1st century BCE–2nd century CE

Dates and time

• The app shows dates from CMS date fields in US style (December 22, 2022). In running text, you can use US style or British style (22 December 2022), but use the same style throughout the text.
• Months: In both styles, spell out the names of months.
• In running text, make sure to add a comma after the year for US-style dates: “On December 22, 2022, she went to the Metropolitan Museum of Art.”
• Decades: Refer to decades as the 1960s or the sixties, not the 1960’s. Use an apostrophe instead of the first two digits only when you refer to more than one decade: the 1950s and ’60s.
• Time: Include lowercase a.m. and p.m., preceded by a space: The gallery talk begins at 10:30 a.m. and the opening reception starts at 7:00 p.m.