Learning Objective:

  • Identify when to use words to refer to numbers and when to use Arabic numerals.

Writers usually write out numbers they can write in a word or two and use Arabic numeralsArabic numerals are the ten digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. (0, 1, 2, 3...) to express larger numbers. However, most writers also follow a set of general guidelines about which numbers should be written out and which should be expressed in numerals. In this lesson, you will learn when to use words and when to use numerals to express various numbers.


Numbers should be written out in these situations:

  1. Numbers expressed in two words or less. Write out and hyphenate any number between twenty-one and ninety-nine. Numbers outside this range do not require a hyphen.

Eleven students

One hundred books

Seventy-nine animals

Thirty-four days

Fifty-five miles per hour

  1. Large rounded numbersNumbers that have been increased or decreased to the nearest whole number. Examples: 1,050,129.88 is rounded down to 1,050,000.00.Numbers that have been increased or decreased to the nearest whole number. Examples: 1,050,129.88 is rounded down to 1,050,000.00 or estimated numbersNumbers that are not exact, but instead formed from an educated guess, usually a rounded number. Examples: about fifty million..

Five trillion

Five thousand

Seven hundred

  1. Numbers at the beginning of a sentenceA group of words, phrases, or clauses that expresses a complete thought. A complete sentence has these characteristics: a capitalized first word, a subject and a predicate, and end punctuation, such as a period (.), question mark (?), or exclamation mark (!).. If the number is so large that it would be awkward to write out, rephrase the sentence so that the number is not the first word.

Four hundred and two staff members are in that unit. This could be rephrased to avoid the number at the beginning of the sentence: There are 402 staff members in that unit.

Twenty-five trucks arrived with supplies.

  1. Numbers in dialogueSpoken conversation described in written form, such as the script for a movie..

"Sabrina swam five hundred and seven laps," he marveled.

"I put two hundred and twenty pieces of candy in the jar," she announced.

"How long will it take you to run a hundred and thirty-five miles?" he asked.

  1. CenturiesA period of one hundred years. Example: the twentieth century includes the years from 1901 to 2000. and decadesA period of ten years. Example: the decade of the nineteen-nineties includes the years from 1990 to 1999.. These should be lowercase.

The nineteenth century

The eighties

The roaring twenties

  1. OrdinalA number that shows order. Examples: first, third, fifteenth. numbers, such as first, second, and third

Her first birthday

My second cupcake

His fifth time around the track

  1. Simple fractions

One fourth of an ounce

One half of a cake

Two thirds of the pie

  1. Time of day with "o'clock" and on the half and quarter hour.

Five o'clock

Half past two

A quarter past ten


Arabic numerals are the ten digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. The following types of numbers are usually expressed as Arabic numerals:

  1. DecimalsA number that is written with a dot between the whole number and the part of the number that is less than one. Examples: 3.75 grade point average; 8.5 ounces.

7.5 ounces

2.5 grams

3.13 pounds

  1. Specific time of day. Use noon or midnight instead of 12.

3:35 p.m.

4:47 a.m.

12:25 p.m.

  1. Dates and years

July 22, 1954

April 3, 1966

September 9, 2011

  1. Scores

The final score was 28 to 14.

She won the game 8 – 6.

He never recovered from the 15 – 14 loss.

  1. Money references

He owed her $216.30.

She gave him $14.65.

Her change was $4.23.

  1. Mixed numbers

Mix in 3 ½ cups of flour.

Her waist was 25 ¼ inches around.

Give him 2 ¼ tablespoons of the medicine after every meal.

Other Rules

There are a couple of other rules to keep in mind when you use numbers in your writing:

  1. Be consistent.

It is important to treat related numbers in a sentence consistently. If you choose to use Arabic numerals, then use them throughout that sentence. The same is true if you choose to write out numbers. You can bend the guidelines for using numbers if you have a purpose and are consistent.

Incorrect: Each of the 12 children sorted out seventy-five cans of food for donation.

Correct: Each of the twelve children sorted out seventy-five cans of food for donation.

Also correct: Each of the 12 children sorted out 75 cans of food for donation.

  1. When in doubt, check your style guideA set of rules for punctuation, grammar, and other facets of writing, used to produce consistency and promote understanding. Different publications and types of writing often follow different style guides. Well-known style guides in the U.S. include The Chicago Manual of Style, the MLA Style Manual, and the Associated Press Stylebook.. While the general rules above will suit most situations, there is some variation between MLAA grammar and reference guide used mainly by students and scholars writing about the humanities (languages and literature). , APAA set of guidelines for citing sources used in literary and academic writing. APA style is most commonly used in the social sciences., APA punctuation and grammar guide used mainly in journalism, public relations, and advertising., and The Chicago Manual of StyleA set of guidelines for grammar, punctuation, and citations, widely used by students, editors, and general interest publications..