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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Let's examine some of the rules that dictate when apostrophes are used and where they should be placed in a word.
In “Understanding Punctuation,” we covered some of the most common punctuation marks used in English writing. Now, let’s look at a few more punctuation marks in further detail.
Check out our free advice on two tricky punctuation marks: the semicolon and colon.
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Numbered, Vertical ("Display"), and Bulleted Lists
Writing and reference manuals offer different advice for creating lists. It seems that as long as you're consistent within your document, you can devise just about any means you want for creating your lists, whether you want them as run-in lists (built into the flow of your text) or as vertical lists (indented and stacked up). Technical writing may have its own requirements in this regard, and you should consult a technical writing manual for specific rules. Use parentheses around the numbers (no periods after the number, though) when using a run-in list:
I have three items to discuss: (1) the first item; (2) the second item; and (3) the third item.
Use semicolons to separate the items, whether they're expressed as fragments or full sentences.
For a vertical list (sometimes called a display list), you may choose to capitalize the items or not, and you may choose to put a comma after each item or not. (If you use commas, put a period after the last item.)
We will now review the following three principles:
- fairness in recruiting
- academic eligibility
- scholarly integrity
Your choice to capitalize or not may depend on how elaborate your lists are and how many of them you have in your text. If a vertical list contains complete sentences or lengthy and complex items, you may prefer to end each element in the list with a semicolon, except for the last element, which you will end with a period.
Most coaches conform to three basic principles in recruiting new players:
- Look for players first who can fill those positions you will need the subsequent year;
- Look for players who are "court smart" as opposed to being merely athletic;
- Look for players who are academically eligible and who have an academic purpose in going to college.
Although the elements in the list above begin with capital letters, that is not absolutely necessary. Notice that there is no "and" at the end of the next-to-last element (although some reference manuals allow for or recommend its use). Although we have used numbers for this list, bullets would work equally well if numbering seems inappropriate or irrelevant. The list below is based on a format suggested by the New York Public Library's Writer's Guide to Style and Usage:
Most coaches conform to three basic principles in recruiting new players
- Look for players first who can fill those positions you will need the subsequent year
- Look for players who are "court-smart" as opposed to being merely athletic
- Look for players who are academically eligible and who have an academic purpose in going to college
Note that this format does not include a period even at the end of the last element. Most writers, however, want to use some kind of punctuation in their listed items. When the introductory statement is a complete sentence, you can end it with either a period or a colon. Use a colon if the sentence is clearly anticipatory of the list, especially if it contains phrasing such as the following or as follows. A colon is also appropriate if the list that follows will be numbered or will establish a priority order. If the introductory statement is not a complete statement, however, neither a period nor a colon would be appropriate since that would interrupt the grammatical structure of the statement; use either no punctuation or try the dash technique noted above.
Listing Names in Alphabetical Order
Putting people's names in alphabetical order is done on a letter-by-letter basis, taking into consideration all the letters before the comma that separates the last from the first name. Omit titles (such as Lady, Sir, Sister), degrees (M.D., Ph.D.), etc., that precede or follow names. A suffix that is an essential part of the name such as Jr., Sr., or a roman numeral appears after the given name, preceded by a comma. (Ford, Henry J., III or Pepin, Theophilus, Jr.)
Beethoven, Ludwig van (The van or von in Dutch or German names, if not capitalized by family usage,appears after the first name; if capitalized, it appears before the last name and determines the alphabetical order.)
Deere-Brown, Juan (Ignore the hyphen.)
Dante Alighieri (Some Italian names of the 15th century or before are alphabetized by first name)
de Gaulle, Charles (With French names, the de goes before the last name when the last name contains only one syllable. See de Maupassant, below.)
Ford, Henry E., III
Garcia Lorca, Federico (Use full surnames for Spanish names.)
López y Quintana, María
Maupassant, Guy de
O'Keeffe, Georgia (Ignore the apostrophe.)
Pepin, R. E.
Pepin, Theophilus, Jr.
Rueda, Lope de (For Spanish names, de comes after the first name)
Saint-Exupéry, Antoine de
San Marco, Josefina
St. Denis, Ruth
Von Braun, Werner (See Beethoven, above.)