If you are like me, then you have asked yourself this question several times. As an author, the answer is important. After all, you want your manuscript to be as professional as possible. Here are some general rules that make it easier to decide:
1) Always spell out numbers at the beginning of a sentence.
2) Always spell out numbers from 2,100 to 9,900 when they are expressed only in
examples: The auditorium held twenty-one hundred people.
The auditorium held 2,340 people.
3) Spell out numbers of streets under twenty, of centuries, of sessions of Congress, of
military bodies, of political divisions and subdivisions as well as ages of people and
examples: East Twentieth Street
the seventeenth century
the Eighth Congress, second session
the One Hundred and Sixty-seventh Infantry
Ninth Congressional District, Fifty-second Ward
a one-hundred-and-four-year-old tree
men between thirty and forty
4) Spell out sums in cents up to one hundred
example: four cents ninety-eight cents
5) Spell out dates when the day precedes the month or the month is missing.
example: The fifth of May......
On the fifth we.......
On March 2, 1892.....
On June 3rd, ....
6) Use numerals when doing technical writing or when it is important for the reader to do
the math and in siting measurements, page numbers and house numbers. Remember
street numbers over twenty are written in numerals.
examples: 75 m.p.h.
3 ft., 9 in.
page 39, line 18
3648 Fifth Avenue
29 East 60th Street
7) Use numerals for the hours of the day when A.M. or P.M.* is used.
example: The meeting was over by 6:00 P.M., but we....
The meeting was over at six, but we.....
(*Printed matter uses small capitals for the abbreviations A.M. and P.M.)