1. Introduction

2. Substantive Writing
3. Mechanics of Writing
3.1 Abbreviations and Names
3.2 Illustrations: Captions and Legends
3.3 Notes and Bibliographies
3.4 Numbers and Dates
3.5 Punctuation
3.6 Spelling and Special Terms
4. Editorial Process
5. Editorial Support
6. Collection Framework
6.1 About the Collection
6.2 Acknowledgments
6.3 Building the Digital Collection
6.4 Cataloging the Collection
6.5 Copyright and Other Restrictions
6.6 Related Resources
6.7 Scope and Content Note
6.8 Selected Bibliography
6.9 Special Presentations
6.10 Other Components
7. Learning Page
8. Today in History
9. Glossary

3.4 Numbers and Dates

This section covers numbers, dates, and form of inclusive numbers. All guidelines and examples follow the Chicago Manual (8.1-80). As numbers and dates appear frequently in collection frameworks, especially in the Scope and Content Note, the guidelines are intended to clarify NDLP style practices.


Guidelines for spelling out numbers:

  • Spell out one through one hundred.

  • Spell out numbers when used approximately: "About a hundred soldiers were killed."

  • Spell out a number used as the first word of a sentence (Chicago 8.9-10).

Numbers in series: When enumerating a series, use numerals:

This collection contains 7 audiorecordings, 15 videorecordings, and 400 photographs.

Numbers in the same sentence but not part of the quantified category may be treated differently:

This collection contains 7 audio-recordings and 15 video-recordings from twenty-three states and 400 photographs by ten authors.

Consistency: When small and large numbers occur together in a group, set them all in numerals for consistency. When listing sets of numbers, Chicago 8.8 advises that "if you must use numerals for one of the numbers in a given category, then for consistency's sake use numerals for them all."

There are 25 photographs in the first box, 56 in the second box, and 117 in the third box, making a total of 198 photographs in the three boxes.

Quantities (Chicago 8.3-31):

  • Units of measurement (Chicago 8.15) in running text should be spelled out. When many units of measurement appear together in text, use numerals with abbreviations (e.g., 9 g, 10 mph).

  • Express round numbers above one million in numerals and words (e.g., 20 million).

  • For percentages (Chicago 8.17-18), use numerals and spell "percent" (e.g., 20 percent). In tables and where many numbers appear, use %.

  • Use commas in four-digit numbers (e.g., 4,508) except where the number is a page number (e.g., 1409).

Fractions (Chicago 8.14) are hyphenated as either adjectives or nouns (e.g., a two-thirds majority, two-thirds of those present). For decimal fractions (Chicago 8.17), use numerals (e.g., 3.14, 0.02).

Use numerals for numbered items such as parts of a book (Chicago 8.32) (e.g., chapter 5, part 2, page 35, volume 4).


Guidelines for spelling out numbers: (Chicago 8.33-46)

The year alone (Chicago 8.34) should be expressed in numerals, unless it is at the beginning of a sentence (Chicago 8.9). Era designations (Chicago 8.41) should be given in capitals, with the following style for periods and spacing: A.D. 1800, 75 B.C.

The day of the month (Chicago 8.36) in running text, notes, and bibliographies is written in the sequence month-day-year, with the year set off by commas:

October 6, 1966

On October 6, 1966, nothing happened.

Write the day of the month as a cardinal number (e.g., April 18, not April 18th).

Month and year (Chicago 8.39) are written in the sequence month-year with no internal punctuation (e.g., April 1993).

Centuries and decades (Chicago 8.40) should be spelled out in lowercase letters (e.g. ninth century, twentieth century). Spell out decades (the sixties, the seventies) or if the decade is identified by the century, write them as plural numerals (1920s, 1880s).

Compound adjectives should be hyphenated (e.g., a twentieth-century school of thought).

Time of day (Chicago 8.47) normally should be spelled out in text (e.g., quarter of four, noon, seven o'clock), but for emphasis write time in numerals, capitalizing A.M. and P.M. (2:30 P.M., 7:30 A.M.)


Form of Inclusive Numbers

Guidelines for form of inclusive numbers (Chicago 8.68-73):

Inclusive numbers: Follow this model, which appears in Chicago 8.69:

Less than 100 Use all digits 3-10, 71-72, 96-117
100 or multiple of 100 Use all digits 100-104, 600-613, 1100-1123
101 through 109 (in multiples of 100) Use changed part only, omitting unneeded zeros 107-8, 505-17, 1002-6
110 through 199 (in multiples of 100) Use two digits, or more if needed 321-25, 415-532, 1536-38, 1496-504, 14325-28, 11564-78, 13792-803

Separating numbers with dashes (Chicago 8.68): Always write "167-72," never "from 167-72." As the dash implies 'from' and 'to,' it is redundant to use the words as well as the dash. Without the dash, however, write "from 167 to 172."

Inclusive years (Chicago 8.71):

When referring to years within the same century but after the first year of that century, use this style:

  • the war of 1914-18

  • 1968-72

  • the years 1701-4

  • 1701-68
When referring to different centuries or a time span when the century changes, repeat all the digits:

  • the years 1597-1601

  • the winter of 1900-1901

  • fiscal year 2000-2001
Titles (Chicago 8.72):

When inclusive years occur in titles, express all the digits:

The Coolidge Era and the Consumer Economy, 1921-1929.
If, however, the title of a published work contains abbreviated inclusive dates, the abbreviation should be retained.


When displaying the span of an individual's life, express all the digits:

  • George Washington (1732-1799)
  • Calvin J. Coolidge (1872-1933)

October 2000