Numbers

In most cases, spell out numbers zero to nine. Use the numerical form for numbers 10 and above.

However, when beginning a sentence with a number, always spell out.

Also, use the numerical form for amounts of money and for percentages.

Dates

Use the cardinal form instead of the ordinal form.

September 24th, 2017

September 24, 2017

Include the year if there is potential for confusion.

Times

Include the “:00” if you mean to indicate the exact time.

Use “a.m.” or “p.m.” (lowercased and with unspaced periods)

Replace “12:00 p.m.” with “noon,” and “12:00 a.m.” with “midnight.”

For a range of time or date, either use an unspaced en dash to separate the items or use both “from” and “to.” Don't combine the en dash with “from” or use “to” without “from.”

7:30 a.m. to 10:30 p.m.

from 7:30 a.m.–10:30 p.m

from 7:30 a.m. to 10:30 p.m.

7:30 a.m.–10:30 p.m.

If both times are in the morning or in the evening, don’t repeat the “a.m.” or “p.m.”

Breakfast was 7:00–10:00 a.m.

Breakfast was from 7:00 to 10:00 a.m.

Avoid other forms of repetition.

June 10–June 15

June 10–15

 

1996–1999

1996–99

Ordinals

The letters in ordinal numbers should not appear as superscripts.

Cornell celebrated the 150th anniversary of its founding in 2015.