Numbers

In General
Adjacent Numbers
Dates
Footnote Numbers
Inclusive Numbers
Metric Measures
Money
Multiple Numbers in a Sentence
More Than One Kind of Number in a Sentence
Ordinal Numbers
Room Numbers
Social Security Number
Telephone Numbers
Time
Years and Decades

In General The following guidelines apply to the majority of CU writing except for scientific, statistical, technical, and mathematical writing.

• Spell out one to nine. Use numerals for 10 and above.
  When she was a child she wanted to be a professor when she grew up. When she turned 21, she realized that she'd rather be a flight instructor.
  
  Exceptions: Use numerals for percentages,* decimals, credit hours, GPAs, book sections and pages, quantities combining whole numbers and fractions, and when symbols rather than abbreviations are used for units of measure.

  *Use the word percent in formal running text. Use the percent sign in tables, charts, scientific and statistical copy, and some informal and promotional copy. Whichever you choose, be consistent throughout a document.

  We printed the first draft on 8.5" X 11" paper.

  In his first semester, when he carried 16 credit hours, he earned a 3.10 GPA while spending 30 percent of his time on a work-study job.

  You'll find the answer in Chapter 2 on page 31.

  She gave five dollars to the CU Foundation, which was 8 percent of her annual dividend check.

  Her brother gave $5.50 to the CU Foundation.

  Her sister gave $5 million to the CU Foundation.

  In the following table, 3 mi. and 75 ft. are approximations.

• Spelling out large round numbers is preferred.
  She gave the museum more than a hundred thousand artifacts.

• Use a combination of numerals and words with numbers in the millions and larger.
  The population increased by 2.3 million.

• Use a comma for numbers with more than three digits unless they represent SAT scores or years.
  Estimated in-state tuition for 1998-99 was $3,038.

  The book, which was published in 1999, has 1,229 pages.

  His combined SAT score was 1135.

• Spell out numbers at the beginning of a sentence or rephrase the sentence to avoid beginning with a number.
  Forty-nine students received the new degree at the May commencement.

• Hyphenate fractions when they are spelled out:
  Two-thirds of the class was late.

  A four-fifths majority voted in favor of the amendment.

The play's set included twelve 8-foot-high plaster pillars.

They distributed 334 twelve-page brochures.

Dates The U.S. preference is for styling dates as: month, day, and year, without the ordinal letters.

New parking permits go on sale January 6, 2000.

NOT New parking permits go on sale January 6th, 2000.

NOT New parking permits go on sale 6 January 2000.

Footnote Numbers Asterisks and superscripts follow punctuation marks (except a dash) in running text and are placed outside a closing parenthesis.

Be sure to enter your social security number,¹ your phone numbers (daytime and evening)² with area code, and your mother's maiden name.³

Inclusive Numbers When dealing with ranges of numbers (such as page numbers and years), carry over all the digits that change and include at least two digits for the second number. Such inclusive numbers use an en dash rather than a hyphen (created with the option key plus hyphen key on the Macintosh).

pages 1,004–05

1991–94

1889–1922

Unless the century changes, inclusive years should be styled with only the last two digits of the second number (1899–1900, but 2001–02). Inclusive years on publication covers, however, can be styled with all four digits of the second number (2001–2002 versus 2001–02) at the designer's discretion.

Note that in running text, the en dash or hyphen is not an acceptable substitute for the word to unless the numbers are in parentheses.

She taught anthropology from 1952 to 1992.

She taught anthropology at CU (1952–1960), Harvard (1960–1988), and Berkeley (1988–1992).

Metric Measures If you are writing for an international audience (for example, writing a brochure to recruit international students for a new program or publicizing an international conference), include metric measurements.

The CU-Boulder Main Campus averages 5,400 feet (1,645 meters) in altitude. The average Boulder daytime high temperature in July is 87°F (31°C).

Money In general: When a relation between two or more similar amounts is expressed, the dollar symbol may or may not be repeated, but use a hyphen to denote range. If fractional amounts over one dollar are used in any reference, be consistent and use them throughout, even if it's a zero amount.

Sweatshirts are available from $20.99 to $75.00.
She invested $1-2 million in the Campaign for Colorado at Boulder.

More Than One Kind of Number in a Sentence When you have numbers in a sentence that refer to more than one class of things, you do not need to make all the numbers numerals if numbers in one of the categories do not exceed nine.

Candidates for student government offices included 12 biology students, 9 political science students, 8 music students, and 7 students from five other majors. (Spell out five because it identifies number of majors, not number of students.)

Multiple Numbers in a Sentence If a sentence includes multiple numbers that apply to the same category of thing, and if one of the numbers must use a numeral, use numerals for all the quantities of that category.

The multiline 44-button telephone is designed to handle more than one call at a time and is equipped with 10 call appearance/feature function buttons, 24 feature function buttons, and 7 display control buttons.

Ordinal Numbers Spell out ordinal numbers from first to ninth.

She placed fourth out of 525 competitors.

The 21st century has been fodder for many imaginative novelists and entrepreneurial visionaries during the latter half of the 20th century.

Room Numbers Campus room numbers should be referred to with the name of the building and the room number, in that order. Do not use the words "room" or "hall."

The Buff OneCard Office is located in Hallett 66.

Social Security Numbers In connection with the Federal Privacy Act of 1974, Section 7(b), when disclosure of the social security number is requested by the university, the request should be marked with an asterisk or footnote number. The footnote should read: For record keeping and identification.

Telephone Numbers Now that all local numbers require use of the area code, do not put the area code in parentheses. Instead, simply use a second hyphen: 303-735-1079.

Time Use numerals with a.m. and p.m. (small caps or lowercase letters) to indicate specific times. Use noon and midnight in place of 12:00 p.m. and 12:00 a.m., respectively, for clarity.

The lecture will begin at 2:30 p.m.

I'll extend office hours this week until about five o'clock.

Years and Decades There are multiple formats for referring to decades. In running text, spelling out the decade (first example) or using the full numeric decade (second example) is preferable. Use the abbreviated numeric decade format in very informal copy or in lists where space is limited. Do not use an abbreviated format if there could be any confusion about the century. Do not use an 's in numeric decades (1880s or '80s, not 1880's or '80's).

the eighties

the 1880s

the '80s

Use the correct placement for A.D. and B.C. (small caps).

Hannibal died in 183 BC

King George IV died in AD 1830.

Unless the century changes, inclusive years should be styled with only the last two digits of the second number (1899–1900, but 2001–02). Inclusive years on publication covers, however, can be styled with all four digits of the second number (2001–2002 versus 2001–02) at the designer's discretion.