Except for a few basic rules, spelling out numbers vs. using figures (also called numerals) is largely a matter of writers' preference. Again, consistency is the key.
Policies and philosophies vary from medium to medium. America's two most influential style and usage guides have different approaches: The Associated Press Stylebook recommends spelling out the numbers zero through nine and using numerals thereafter—until one million is reached. Here are four examples of how to write numbers above 999,999 in AP style: 1 million; 20 million; 20,040,086; 2.7 trillion.
The Chicago Manual of Style recommends spelling out the numbers zero through one hundred and using figures thereafter—except for whole numbers used in combination with hundred, thousand, hundred thousand, million, billion, and beyond (e.g., two hundred; twenty-eight thousand; three hundred thousand; one million). In Chicago style, as opposed to AP style, we would write four hundred, eight thousand, and twenty million with no numerals—but like AP, Chicago style would require numerals for 401; 8,012; and 20,040,086.
This is a complex topic, with many exceptions, and there is no consistency we can rely on among blogs, books, newspapers, and magazines. This chapter will confine itself to rules that all media seem to agree on.
Rule 1. Spell out all numbers beginning a sentence.
Twenty-three hundred sixty-one victims were hospitalized.
Nineteen fifty-six was quite a year.
Note: The Associated Press Stylebook makes an exception for years.
Example:1956 was quite a year.
Rule 2a. Hyphenate all compound numbers from twenty-one through ninety-nine.
Forty-three people were injured in the train wreck.
Twenty-seven of them were hospitalized.
Rule 2b. Hyphenate all written-out fractions.
We recovered about two-thirds of the stolen cash.
One-half is slightly less than five-eighths.
However, do not hyphenate terms like a third or a half.
Rule 3a. With figures of four or more digits, use commas. Count three spaces to the left to place the first comma. Continue placing commas after every three digits. Important: do not include decimal points when doing the counting.
Note: Some choose not to use commas with four-digit numbers, but this practice is not recommended.
Rule 3b. It is not necessary to use a decimal point or a dollar sign when writing out sums of less than a dollar.
Not Advised:He had only $0.60.
He had only sixty cents.
He had only 60 cents.
Rule 3c. Do not add the word "dollars" to figures preceded by a dollar sign.
Incorrect: I have $1,250 dollars in my checking account.
Correct: I have $1,250 in my checking account.
Rule 4a. For clarity, use noon and midnight rather than 12:00 PM and 12:00 AM.
AM and PM are also written A.M. and P.M., a.m. and p.m., and am and pm. Some put a space between the time and AM or PM.
Others write times using no space before AM or PM.
For the top of the hour, some write 9:00 PM, whereas others drop the :00 and write 9 PM (or 9 p.m., 9pm, etc.).
Rule 4b. Using numerals for the time of day has become widely accepted.
The flight leaves at 6:22 a.m.
Please arrive by 12:30 sharp.
However, some writers prefer to spell out the time, particularly when using o'clock.
She takes the four thirty-five train.
The baby wakes up at five o'clock in the morning.
Rule 5. Mixed fractions are often expressed in figures unless they begin a sentence.
We expect a 5 1/2 percent wage increase.
Five and one-half percent was the expected wage increase.
Rule 6. The simplest way to express large numbers is usually best.
Example:twenty-three hundred (simpler than two thousand three hundred)
Large round numbers are often spelled out, but be consistent within a sentence.
Consistent:You can earn from one million to five million dollars.
Inconsistent:You can earn from one million dollars to 5 million dollars.
Inconsistent:You can earn from $1 million to five million dollars.
Rule 7. Write decimals using figures. As a courtesy to readers, many writers put a zero in front of the decimal point.
The plant grew 0.79 inches last year.
The plant grew only 0.07 inches this year.
Rule 8a. When writing out a number of three or more digits, the word and is not necessary. However, use the word and to express any decimal points that may accompany these numbers.
one thousand one hundred fifty-four dollars
one thousand one hundred fifty-four dollars and sixty-one cents
Simpler:eleven hundred fifty-four dollars and sixty-one cents
Rule 8b. When writing out numbers above 999, do not use commas.
Incorrect: one thousand, one hundred fifty-four dollars, and sixty-one cents
Correct: one thousand one hundred fifty-four dollars and sixty-one cents
Rule 9. The following examples are typical when using figures to express dates.
the 30th of June, 1934
June 30, 1934 (no -th necessary)
Rule 10. When spelling out decades, do not capitalize them.
Example:During the eighties and nineties, the U.S. economy grew.
Rule 11. When expressing decades using figures, it is simpler to put an apostrophe before the incomplete numeral and no apostrophe between the number and the s.
Example:During the '80s and '90s, the U.S. economy grew.
Some writers place an apostrophe after the number:
Example:During the 80's and 90's, the U.S. economy grew.
Awkward:During the '80's and '90's, the U.S. economy grew.
Rule 12. You may also express decades in complete numerals. Again, it is cleaner to avoid an apostrophe between the year and the s.
Example:During the 1980s and 1990s, the U.S. economy grew.
You may have noticed a theme when it comes to the English language: most rules are not completely standardized. This (somewhat frustrating) fact is especially true when it comes to spelling out numbers. Should you write them out in words or leave them as numerals? To write numbers properly, you will have to identify potential differences between major style guides (such as MLA, APA, and Chicago, to name a few) because these guides often outline different rules for using numbers in writing.
To make it easier, let's use an example. Say you're working on a paper evaluating the importance of the local public library in your community. The document will make use of small numbers, large numbers, decades, and statistics. Thankfully, when using numbers in writing, you can count on a few conventions that apply to most situations; just be sure to consult your specific style guide if one has been assigned.
Small and Large Numbers
A simple rule for using numbers in writing is that small numbers ranging from one to ten (or one to nine, depending on the style guide) should generally be spelled out. Larger numbers (i.e., above ten) are written as numerals.
For example, instead of writing, "It cost ten-thousand four-hundred and sixteen dollars to renovate the local library," you would write, "It cost $10,416 to renovate the local library."
The reason for this is relatively intuitive. Writing out large numbers would not only waste space but could also be a major distraction to your readers.
Beginning a Sentence
Here is a rule that you can truly rely on: always spell out numbers when they begin a sentence, no matter how large or small they may be.
Incorrect: 15 new fiction novels were on display.
Correct: Fifteen new fiction novels were on display.
If the number is large and you want to avoid writing it all out, rearrange the sentence so that the number no longer comes first.
Revised: There were 15 new fiction novels on display.
Whole Numbers vs. Decimals
Another important factor to consider is whether you are working with a whole number or a decimal. Decimals are always written as numerals for clarity and accuracy.
To revisit our library example, perhaps circulation statistics improved in 2015. If a number falls in the range of one to ten and is not a whole number, it should be written as a numeral.
Incorrect: The circulation of library materials increased by four point five percent in 2015.
Correct: The circulation of library materials increased by 4.5% in 2015.
When two numbers come next to each other in a sentence, be sure to spell out one of these numbers. The main purpose of this rule is to avoid confusing the reader.
Incorrect: There were 12 4-year-old children waiting for the librarian to begin story time.
Correct: There were twelve 4-year-old children waiting for the librarian to begin story time.
Correct: There were 12 four-year-old children waiting for the librarian to begin story time.
Decades and Centuries
Decades or centuries are usually spelled out, especially if the writing is formal.
Incorrect: The library was built in the '50s.
Correct: The library was built in thefifties.
If you are referring to a specific year (e.g., 1955), use the numeral.
Always strive for consistency, even if it overrides a previous rule. For example, if your document uses numbers frequently, it is more appropriate for all numbers to remain as numerals to ensure that usage is uniform throughout. Similarly, if a single sentence combines small and large numbers, make sure that all the numbers are either spelled out or written as numerals.
Incorrect: The library acquired five new mystery novels, 12 new desktop computers, and 17 new periodicals.
Correct: The library acquired 5 new mystery novels, 12 new desktop computers, and 17 new periodicals.
Let's complicate things a bit, shall we?
If your work must follow the rules of a specific style guide, understand that they all have rules for spelling out numbers that may differ slightly from the rules listed above. For example, MLA style indicates that writers may spell out numbers if they are not used too frequently in the document and can be represented with one or two words (e.g., twenty-four, one hundred, three thousand). APA style advises that common fractions (e.g., two-thirds) be expressed as words. A number of specific rules for spelling out numbers are outlined in section 9.1 of the Chicago Manual of Style.
Your ultimate authority will always be a style guide, but in the absence of one, following the rules outlined above will help you be consistent in your use of numbers in writing.
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