A Few Simple Rules for Expressing Numbers in Your Writing

A Few Simple Rules for Expressing Numbers in Your Writing When you refer to a number in your writing, you often have to decide whether to use a numerical expression/figure or spell it out as a word. This article discusses numbers, how to write them correctly, and when to use numerical expressions instead.General rulesRelated numbers should be expressed consistently. For example, if you choose to use figures because one of the numbers is greater than nine, use figures for all of the numbers in that category. If you choose to spell out numbers because one of the numbers is a single digit, spell out all numbers in that category. For example:Right: two apples, six oranges, four pears, and three bananasWrong: two apples, 6 oranges, four pears, and 3 bananasIf a passage includes numbers that follow one another, one is spelled out and the other is represented with a figure.Unclear: The club celebrated the birthdays of 6 90-year-olds who were born in the city. (This may cause the reader to read 690 as one number.)Clearer: The club celebrated the bi rthdays of six 90-year-olds who were born in the city.Rules for spelling out numbersThe rules of usage vary, but small numbers, such as whole numbers smaller than ten, should be spelled out. This is the one rule that is fairly uniform among all rulebooks. Most style guides also include all numbers that can be expressed in one or two words. Figures are recommended for the other cases. For example:Exactly three poundsTwo thousand dollarsAbout twenty-six yearsThirty-two peopleJust 268 days until ChristmasCost $46.151,238 tons116.3 gallonsAnother widely accepted rule is to write out a number if it begins a sentence. For example:Right: Six percent of the group failed.Wrong: 6% of the group failed.You may need to reword sentences to avoid spelling out large numbers. For example:Right: Fans bought 400,000 copies of her new book on the first day.Wrong: 400,000 copies of her book were sold on the first day.In English, the comma is used as a thousands separator and the period is used as a dec imal separator to make large numbers easier to read. Thus, you should write the size of Alaska as:Right: 571,951 square milesWrong: 571951 square miles.If the number is rounded or estimated, spell it out. Rounded numbers over a million are written as a numeral plus a word:Right: About 400 million people speak Spanish natively,Wrong: About 400,000,000 people speak Spanish natively.Hyphenate a number written as two words if it is under one hundred. For example:There are twenty-two students in my class.Use a hyphen to separate the numerator from the denominator in written fractions. For example:Two-thirds of the class chose the correct answer.Rules for using figuresThe following should be expressed as figures.Exact measurements followed by symbols or abbreviations: 55 m.p.h.Exact amounts of money: $110.79Decimals and fractions: 2.5, 3/5Percentages, scores, or statistics: 38%, score of 10-1Volume, chapter, and page numbers: Vol. I, Chapter 12, page 87Act, scene, and line numbers: Act II I, Scene 2, lines 23-27PlacesFigures are generally used for addresses. For example:16 Tenth Street350 West 114 StreetTimeUse numerals with the time of day when exact times are being emphasized or when using A.M. or P.M. For example:8:00 A.M.However, use noon and midnight rather than 12:00 P.M. and 12:00 A.M.Normally, spell out the time of day in text even with half and quarter hours. With oclock, the number is always spelled out. For example:eight oclock in the morningDatesIt is generally acceptable to express a decade by spelling it out or writing it as a figure. When expressing a decade as a figure, do not use an apostrophe between the year and the s, i.e., 1980s. When spelling out a decade, use lower case letters, i.e., the eighties.In general, do not use st, nd, rd, and th after dates to indicate ordinals.Right: We will meet again on April 15.Wrong: We will meet again on April 15th.Here are a few more examples of dates:December 12, 1965 or 12 December 1965A.D. 1066in 1900from 19 71–72 or from 1971–1972Expressing numbers in mathematics and the sciencesUse an en dash, not a hyphen, to indicate a closed numeric range, i.e., 100–110.Insert a space on either side of mathematical operators (-, +, =, etc.) or symbols unless they directly precede a number to indicate a value (There should not be a space between a number and a percentage sign, i.e., 100%.Preferably abbreviate units of measurement when used with figures, but spell them out when not preceded by figures.Write decimals in figures. Put a zero in front of a decimal unless the decimal itself begins with a zero.Please keep in mind that this article discusses general rules regarding the expression of numbers in writing. In business and academia, you should always consult the applicable style guide. For example, the APA Publication Manual and the Chicago Manual of Style have extensive sections devoted to the use of numbers in technical papers.