Expressing Numbers Chicago

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Use Numerals for the Following:

1. Whole numbers plus fractions, e.g., 6 ½ yards, decimal fractions, and whole numbers in close proximity to decimal fractions

2. Time expressed in exact terms, e.g., 11:00 a.m.

3. All numbers in equations and formulas

4. All federal, state, and interstate highways

5. Percentages (In humanities papers, use “percent.” In scientific papers and statistical studies, use the percent sign, e.g., 45 percent of the electorate and 75% of the ants, respectively.)

6. Parts of books (Note: the words chapter, part, appendix, table, figure, etc. are lowercase in the text.), e.g., chapter 2, volume 4, and table 15

7. Days (given as cardinal numbers) and years standing alone unless found at the beginning of sentences, e.g., 2000

8. Numbers designating local branches of labor unions and fraternal lodges, e.g., United Auto Workers, Local 890, and Typographical Union no. 16

9. In scientific contexts

a. Physical quantities and units of time, whether whole numbers or fractions, followed by an abbreviated form of the unit, e.g., 50 km, 4.5 L, and 240 V

b. All numbers greater than nine (cardinals and ordinals)

10. Monetary quantities are either given in numerals (with dollar or cent signs) or in words (with the words dollars or cents). Whichever you choose, be consistent.

Use Words for the Following:

1. Any number beginning a sentence and round numbers (hundreds, thousands, etc.)

2. Particular centuries (lowercase), e.g., the twenty-first century and the eighteen hundreds. Decades are either spelled out or expressed with numerals, e.g., the nineties or the 1990s. Whichever form you choose, be consistent.

3. Time expressed in quarter and half hours, hours followed by o’clock, and noon and midnight, e.g., half past three and five o’clock

4. Days when not accompanied by the month or year (given as ordinals)

5. Numbers one hundred or less designating successive dynasties, governments, and other governing bodies; military units; and political or judicial divisions, e.g., the Eighteenth Dynasty, Fifth Republic, Second Continental Congress, and the Fourth Infantry Division

6. Numbers that are part of the names of places of worship, e.g., the Fourth Presbyterian Church and the Twenty-first Church of Christ, Scientist

7. Numbered streets of one hundred or less, e.g., First Avenue and Ninety-Fifth Street

8. In nontechnical contexts

a. Whole numbers from one to one hundred (cardinals and ordinals); physical quantities when between one and one hundred; and simple fractions, e.g., one and ninety-nine; twenty degrees; three-by-five cards; and three-quarters of the book

9. In scientific/financial contexts

a. Single digit numbers (cardinals and ordinals)

Use Words and Numerals for the Following:

1. Very large numbers (millions or more), especially when the quantity is fractional, e.g., 2.3 million and 25 million