A manual for writers of research papers, theses, and dissertations, Ninth edition - Kate L. Turabian 2018

Words or numerals?
Numbers
Style

23.1 Words or Numerals?

23.1.1 General Rule

23.1.2 Special Cases

23.1.3 Percentages and Decimal Fractions

23.1.4 Money

23.1.5 Time

23.1.6 Names with Numbers

23.1.7 Addresses and Thoroughfares

23.1.8 Parts of Published Works

23.1.9 Equations and Formulas

23.2 Plurals and Punctuation

23.2.1 Plurals

23.2.2 Commas within Numbers

23.2.3 Other Punctuation within Numbers

23.2.4 Inclusive Numbers

23.3 Date Systems

23.3.1 Month, Day, and Year

23.3.2 Decades, Centuries, and Eras

23.4 Numbers Used outside the Text

23.4.1 Numbers in Tables, Figures, and Citations

23.4.2 Enumerations

This chapter offers general guidelines for presenting numbers. These guidelines are appropriate for most humanities and social science disciplines, but disciplines that rely heavily on numerical data may have more specific guidelines. If you are writing a paper in the natural or physical sciences, mathematics, or any other very technical field, follow the conventions of the discipline. For style guides in various disciplines, see the bibliography. For advice on numbering the pages and parts of your paper, see the appendix.

If you are writing a thesis or a dissertation, your department or university may have specific requirements for presenting numbers, which are usually available from the office of theses and dissertations. If you are writing a class paper, your instructor may also ask you to follow certain principles for presenting numbers. Review these requirements before you prepare your paper. They take precedence over the guidelines suggested here.

23.1 Words or Numerals?

The most common question in presenting numbers is whether to spell them out in words (twenty-two) or give them in numerals (22). When the number is followed by a unit of measure, you must also decide whether to give that unit in words (percent) or as a symbol (%) or an abbreviation.

The guidelines presented in 23.1—23.3 pertain to numbers used in the text of your paper. For numbers used in tables, figures, and citations, see 23.4.

Unless otherwise specified, numerals here means arabic numerals (1, 2, 3, etc.). For roman numerals (i, ii, iii, etc.), see table 23.1.

Table 23.1. Roman numerals

23.1.1 General Rule

Before you draft your paper, you should decide on a general rule for presenting numbers and follow it consistently. Which rule you choose depends on how often you use numerical data and the conventions of your discipline. For situations in which you might modify this rule, see 23.1.2—23.1.8.

In the humanities and social sciences, if you use numerical data only occasionally, spell out numbers from one through one hundred. If the number has two words, use a hyphen (fifty-five). Also spell out round numbers followed by hundred, thousand, hundred thousand, million, and so on (but see 23.1.2.3). For all other numbers, use arabic numerals. Follow this pattern for numbers that are part of physical quantities (distances, lengths, temperatures, and so on), and do not use abbreviations for the units in such quantities (see 24.5).

After seven years of war came sixty-four years of peace.

The population of the three states was approximately twelve million.

He cataloged more than 527 works of art.

Within fifteen minutes the temperature dropped twenty degrees.

If your topic relies heavily on numerical data, follow a different rule: spell out only single-digit numbers and use numerals for all others.

This study of 14 electoral districts over seven years included 142 participants.

He hit the wall at 65 miles per hour, leaving skid marks for nine feet.

In the sciences, your general rule may be to use numerals for all numbers, except when they begin a sentence (see 23.1.2.1). You may also use abbreviations for quantities (see 24.5).

The mean weight proved to be 7 g, which was far less than predicted.

With any of these rules, use the same principles for ordinal numbers (first, second, etc.) that you use for standard ones. Add st, nd, rd, or th as appropriate.

On the 122nd and 123rd days of his trip, he received his eighteenth and nineteenth letters from home.

23.1.2 Special Cases

In a few common situations, the general rule discussed in 23.1.1 requires modification.

23.1.2.1 NUMBERS BEGINNING A SENTENCE. Never begin a sentence with a numeral. Either spell out the number or recast the sentence, especially when there are other numerals of a similar type in the sentence.

Two hundred fifty soldiers in the unit escaped injury; 175 sustained minor injuries.

or, better,

Of the soldiers in the unit, 250 escaped injury and 175 sustained minor injuries.

When spelling out numbers over one hundred, omit the word and within the term (not two hundred and fifty).

23.1.2.2 RELATED NUMBERS. Ignore the general rule when you have a series of related numbers in the same sentence that are above and below the threshold, especially when those numbers are being compared. In these examples, all are expressed in numerals.

Of the group surveyed, 78 students had studied French and 142 had studied Spanish for three years or more.

We analyzed 62 cases; of these, 59 had occurred in adults and 3 in children.

If you are discussing two sets of items in close proximity, ignore the general rule and, for clarity, spell out all numbers in one set and use numerals for all numbers in the other.

Within the program, 9 children showed some improvement after six months and 37 showed significant improvement after eighteen months.

23.1.2.3 ROUND NUMBERS. Spell out a round number (a whole number followed by hundred, thousand, hundred thousand, million, and so on) in isolation (see 23.1.1), but give several round numbers close together in numerals. You may also express large round numbers in a combination of numerals and words. (See also 23.1.4.)

Approximately fifteen hundred scholars attended the conference.

but

They sold 1,500 copies in the first year and 8,000 in the second.

These changes will affect about 7.8 million people in New York alone.

23.1.3 Percentages and Decimal Fractions

Use numerals to express percentages and decimal fractions, except at the beginning of a sentence (see 23.1.2.1). Spell out the word percent, except when you use many percentage figures and in the sciences, where the symbol % is usually preferred (with no intervening space after the number). Notice that the noun percentage should not be used with a number.

Scores for students who skipped summer school improved only 9 percent. The percentage of students who failed was about 2.4 times the usual rate.

Within this system, the subject scored 3.8, or 95%.

but not

The average rose 9 percentage points.

When you use fractional and whole numbers for the same type of item in the same sentence or paragraph, give both as numerals.

The average number of children born to college graduates dropped from 2.4 to 2.

Put a zero in front of a decimal fraction of less than 1.00 if the quantity expressed is capable of exceeding 1.00. When decimal quantities must be 1.00 or less, as in probabilities, correlation coefficients, and the like, omit the zero before the decimal point.

✵ a mean of 0.73

✵ a loss of 0.08

✵ p < .05

✵ a .406 batting average

For fractions standing alone, follow the general rule (see 23.1.1) for spelling out the parts. If you spell the parts, include a hyphen between them. Express in numerals a unit composed of a whole number and a fraction. If you use a symbol for the fraction, there is no intervening space between the number and the fraction.

Trade and commodity services accounted for nine-tenths of all international receipts and payments.

One year during the Dust Bowl era, the town received only 15/16 of an inch of rain.

The main carving implement used in this society measured 2½ feet.

23.1.4 Money

23.1.4.1 US CURRENCY. If you refer only occasionally to US currency, follow the general rule (see 23.1.1), and spell out the words dollars and cents. Otherwise use numerals along with the symbol $ (or, if needed, ¢). Omit the decimal point and following zeros for whole-dollar amounts, unless you refer to fractional amounts as well.

Rarely do they spend more than five dollars a week on recreation.

The report showed $135 collected in fines.

Prices ranged from $0.95 up to $10.00.

Express large round numbers in a combination of numerals and words.

The deficit that year was $420 billion.

23.1.4.2 OTHER CURRENCIES. For currencies other than that of the United States, follow the pattern for the US dollar. Most currencies put unit symbols before numerals. Even though European nations represent decimal points with commas instead of periods, you may use periods, except in direct quotations from sources. In contexts where the symbol $ may refer to non-US currencies, these currencies should be clearly identified.

When she returned, she had barely fifty euros to her name.

The household records show that it cost only £36.50.

Its current estimated worth is ¥377 million.

If you subtract Can$15.69 from US$25.00, . . .

Most European nations now use the unified currency called the euro (€), but if you are writing about topics from the period before 2002, you may encounter such currencies as the French franc (F), German deutsche mark (DM), and Italian lira (Lit). British currency is still expressed in pounds (£) and pence (p.), though before decimalization in 1971, it was expressed in pounds, shillings, and pence (for example, £12 17s. 6d.). Note that billion in traditional British usage as well as in certain languages other than English means a million million, not a thousand million; to avoid confusion, be sure to accurately represent such distinctions.

In more technical contexts, it may be best to use the three-letter codes for current and historical currencies defined by the International Organization for Standardization in standard ISO 4217, which is available on the organization’s website. Use a space between the code and the amount.

If you subtract EUR 15.69 from USD 25.00, . . .

23.1.5 Time

For references to times of day in even increments of an hour, half hour, or quarter hour, spell out the times, with a hyphen between parts. If necessary, specify in the morning or in the evening. You may use o’clock, although it is now rare in research writing.

The participants planned to meet every Thursday around ten-thirty in the morning.

When emphasizing exact times, use numerals and, if necessary, a.m. or p.m. (lowercase and roman; see also 24.4.1). Always include zeros after the colon for even hours.

Although scheduled to end at 11:00 a.m., the council meeting ran until 1:37 p.m.

In either situation, use the words noon and midnight (rather than numerals) to express these specific times of day.

For use of words or numerals in dates, see 23.3.

23.1.6 Names with Numbers

Some types of personal, governmental, and organizational names include numbers given in either words or numerals. (See also 22.1.)

✵ ▪ Leaders. Emperors, sovereigns, or popes with the same first name are differentiated by capitalized roman numerals (see table 23.1).

o Charles V

o Napoleon III

o Elizabeth II

o Benedict XVI

✵ ▪ Family members. Male family members with identical full names are often differentiated with roman or arabic numerals (see also 24.2.1). Note that there are no commas between the name and the numeral, unless the name is inverted, as in a list.

o Adlai E. Stevenson III

o Michael F. Johnson 2nd

o but

o Stevenson, Adlai E., III

✵ ▪ Governments and political divisions. Certain dynasties, governments, governing bodies, political and judicial divisions, and military units are commonly designated by an ordinal number before the noun. Spell out and capitalize numbers through one hundred (with a hyphen between the parts of the number, if relevant); use numerals for those over one hundred.

o Nineteenth Dynasty

o Fifth Republic

o Eighty-First Congress

o 109th Congress

o Fourteenth Congressional District

o Forty-Seventh Ward

o Tenth Circuit

o 101st Airborne Division

✵ ▪ Churches and religious organizations. Spell out and capitalize numbers before the names of churches or religious organizations in ordinal form (with a hyphen between the parts of the number, if relevant).

o Twenty-First Church of Christ, Scientist

✵ ▪ Secular organizations. Express local branches of fraternal lodges and unions in numerals following the name.

o American Legion, Department of Illinois, Crispus Attucks Post No. 1268

o United Auto Workers Local 890

23.1.7 Addresses and Thoroughfares

Follow the general rule (see 23.1.1) for the names of local numbered streets. State, federal, and interstate highways are always designated with numerals, as are street or building addresses and telephone and fax numbers. Note that in text the elements of a full address are separated by commas, except before a zip code. See 24.3.2 for abbreviations in addresses.

The National Park Service maintains as a museum the house where Lincoln died (516 10th Street NW, Washington, DC 20004; 202-426-6924).

Ludwig Mies van der Rohe designed the apartments at 860—880 North Lake Shore Drive.

Interstate 95 serves as a critical transportation line from Boston to Miami.

23.1.8 Parts of Published Works

With the exception of roman-numeral page numbers (as in the front matter of a book; see 16.1.5, 18.1.5), numbers in parts of published works are given in arabic numerals, regardless of the general rule (see 23.1.1) or their appearance in the work itself. See also 22.3.2.3, 23.2.2.

✵ chapter 14

✵ part 2

✵ act 1, scene 3

✵ page 1024

23.1.9 Equations and Formulas

Numbers in equations and formulas are always given as numerals, regardless of the general rule (see 23.1.1). For detailed guidance on presenting mathematical expressions, see chapter 12 of The Chicago Manual of Style, 17th edition (2017).