General Guidance

See CMS 9.5 for guidance on numbers beginning sentences.

See CMS 9.6 for guidance on ordinal numbers.

See CMS 9.7 for guidance on consistency and flexibility with numbers in sentences, particularly when several numbers appear in the same sentence and refer to the same thing.

Inclusive amounts

When the words “thousand,” “billion,” and “million” are used in inclusive amounts, our style is to give the full amounts and use “to” rather than an en dash. The rationale is that if an en dash is used, the span could be misleading.

Example: “$2 billion to $5 billion,” not “$2–$5 billion”

The reason is that “$2–$5 billion” could be interpreted as “two dollars to five billion dollars.” (See also the section Currency.)

Inclusive years

Used as an adjective: When a range of years is used as an adjective modifying a noun, use an en dash between the years. If the range begins and ends during the same century, the first two digits of the second year are not repeated—except that full four-digit dates should be used in book and article titles for our publications. For all other publications, follow how it looked in the original.

Examples: during the 1940–50 period, in the 2000–02 bear market, the 1801–99 famine, the 1492–1604 age of exploration, “Profit Maximizing: 1940–1950,” The 1963–1990 Period of CFA Institute History

Used as a noun: If the range of years is being used as a noun, use full years and an en dash or spell out the words joining the range and use all the digits of both years.

Examples: the fashions of 1607–1610, from 1492 to 1604, between 1975 and 1985

Numbers smaller than one

In formal writing, when a percentage point is less than 1.0, consider the amount singular (e.g., 3.5 bps but 0.12 bp).

Page numbers

No matter how many digits are in the page numbers, use all digits of the second number (except in References).

Examples: 3–10, 21–29, 46–88, 107–109, 1496–1504, 13480–13482

Note: No commas in page numbers.

Phone numbers

Use the following phone number format:

+country code (area code) xxx-xxxx. EXCEPTION: For toll-free numbers, do not include the country code. That is, use (800) 247-8132.

Examples: Contact CFA Institute at +1 (434) 951-5499. Contact us at (800) 955-2345 from the United States or Canada.

Spelling out vs. using numerals

In general, numbers from one through nine are spelled out in text. Numerals are used for 10 and all higher numbers up to 1 million.

Examples: 47, 102, 3,044, 700,000; three to six months; 30–60 months; two to three times; 20–30 times; a three- to six-month period

Very large numbers (1 million and up) are expressed as numerals followed by the appropriate word.

Examples: 5 million, 3 billion, 7 trillion

To abbreviate million, billion, and trillion in tables, figures, or notes, use m, bn, and trn, respectively.

Examples: 5m, 3bn, 7trn

Numerals are used for units of measurement, including percentages, multipliers, and mathematical terms. Always include the initial zero if the number represented is less than zero.

Examples: 1%, 0.12%, 1 inch, 8 gallons, a price multiple of 2 times earnings (but “the economy grew three times as fast as anyone thought it would”), a standard deviation of 2 (but “two standard deviations”), 40 bps

Exception: Spell out zero when it is used alone (that is, not preceding a unit-of-measurement word), but use 0 when zero is used with other numerals.

Examples: 0%–1.5%; ranged from 0 to 25; returns were below zero


Use a comma in index amounts of four or more digits. (See also the Comma section.)

Example: By 2002, the DJIA was way past 8,000.

2 thoughts on “Numbers

  1. Pingback: En Dash | CFA Institute Style Guide

  2. Pingback: Currency | CFA Institute Style Guide

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