Numbers

The following rules pertain to the treatment of numbers in text, specifically, the decision whether to set numbers as numerals or words.

The Basic Rule

Spell out whole numbers below 10. Use numerals for 10 and above.

Examples:

John has three cats.

There were 40 books on the desk.

Her manuscript ran to 571 pages.

Enrollments have risen to a total of 7,891 this year.

Ordinals

Ordinals follow the basic rule.

Consistency

Treat numbers within a category alike within the same context. If normal rules prescribe using numerals for one number, use numerals for all.

Example:

There were 6 participants in January, 9 in May, and 11 in September.

Exceptions to the Basic Rule

First Word in a Sentence

A number used at the beginning of the sentence is always spelled out, regardless of any inconsistency that may result.

Examples:

Three hundred sixty-two students attended orientation.

Fifteen percent of the profits were reinvested.

Nineteen seventy-six was the year of the U.S. bicentennial.

Physical Quantities

In mathematical, statistical, scientific, or technical text, physical quantities (e.g., distances, lengths, areas, volumes) are expressed in numerals. For nonscientifc usage, follow the regular rules, with one exception: quantities that consist of both whole numbers and fractions should be expressed in numerals.

Abbreviations and Symbols

If an abbreviation or symbol is used for the unit of measure, the quantity should always be expressed in numerals.

Example:

65 mph

12'

Percentages and Decimal Fractions

Percentages and decimal fractions are always expressed in numerals. In scientific and statistical texts, use the symbol % for a percentange; in other texts, use the word percentage.

Example:

The likelihood is about 25 percent.

My credit card carries an interest rate of 9.9 percent.

In the current study, 25% of the experimental group completed the task successfully.

A score of 3.8 or higher is exceptional

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