Numbers, Dates, and Times

The following numbers are spelled out in running text:

  • Whole numbers from one through nine
  • Any of these numbers followed by hundred, thousand, million, etc.

In lists and other display type, figures are usually used:

  • Number of first-termers: 453 Total number MBA students: 1,306

Use numerals for dates, times, page numbers, decimal amounts, ages, and percentages, even if they are between 1 and 9:

  • He only got a 2 percent raise.
  • My son turned 3 today.

Spell out percent.

  •  99 percent

Numeric ranges are separated by an en dash unless preceded by “from” or “between”

  • December 21–28
  • From December 21 to 28
  • Between December 21 and 28

Commas may also be used to separate elements of a date range

  • The program will run from May 30, 1996, to June 17, 1997.

Never start a sentence with a figure — spell out the number or restructure the sentence if necessary.

     1976 was the year of the nation’s bicentennial celebration.

     should be revised to read

     The nation celebrated its bicentennial in 1976.

When two kinds of numbers fall together, use a figure for one kind to differentiate between them:

  • There are three 4-credit courses.

The part of the day to which clock time applies is indicated, in regular text as well as tabular matter, by the usual abbreviations:

  • 10 a.m. (before noon)
  • 8 p.m. (after noon)
  • To avoid confusion, use Noon or Midnight, not 12:00 p.m. or 12:00 a.m.
  • The abbreviations a.m. and p.m. should be set in lowercase with periods

When specifying time zones, the School follows the Chicago Manual of Style. Time zones are abbreviated, capitalized, and in parenthesis after the time. 

  • 5 p.m. (EST) 
  • Note: EST during fall/winter and EDT during spring/summer, this applies to other applicable time zones as well

When citing time ranges, use the fewest number of digits possible but use a consistent number of digits.

  • 8–9 a.m.
  • 8:00–9:30 a.m.
  • 8 a.m. to 9 p.m.
  • 8:00 a.m. to 9:30 p.m.
  • 8 a.m. to Noon

Academic or fiscal years should be presented as follows:

  • Fiscal year 2018–19 or FY19

When a range of years crosses a century, use four digits for both years; otherwise, drop the first two digits in the second year

  • 2018–19, but 1999–2000

Use figures to denote centuries later than the ninth:

  • The American economy in the 19th century

Use figures for days of the month:

  • January 1 (not first or 1st)

In numbers in the thousands, use a comma:

  • 1,500 (not 1500)

When referring to times of the day, use only those digits that are necessary:

  • 8 p.m. (not 8:00 p.m.)

Do, however, maintain a consistent number of digits within a given section:

  • The event lasted from 10:30 a.m. to 3:00 p.m.

No apostrophe should be used for pluralizing numbers or letters:

  • the depression of the 1930s
  • a temperature in the high 50s

Do not use a comma between month and year:

  • The visitors are expected in May 1997.

Sums of money of more than 100 dollars are normally expressed by numerals or, for numbers of a million or more, by a mixture of numerals and spelled-out numbers.

  • Most of the homes that went into foreclosure were valued at more than $95,000.
  • She signed a 10-year, $250 million contract.
  • The military requested an additional $7.3 billion.

When referring to sums of money, use only those digits that are necessary.
     $60 (not $60.00)

Telephone Numbers
In US telephone numbers, use hyphens throughout with no spaces.

  • 212-854-8567

For international numbers, include the country code preceded by a plus (which indicates that additional numbers, depending on the origin of the call, are required). For example, a French number looks like this — +33 1 00 00 00 00 — where “33” is the country code for France, “1” designates the Île-de-France region (which includes Paris), and the rest is the usual eight paired digits separated by spaces for French telephone numbers. From the United States, the plus sign signals the 011 needed to initiate an international call; from many other countries, it’s 00.