Section 9.5
Numbers
Unless you are following a style guide that
specifies otherwise, observe the following guidelines in using
numbers.
- In general, use arabic numerals instead of words in
scientific and technical writing for both cardinal and
ordinal numbers:
| 3 subroutines |
6 braces |
61 amino acids |
| the 3rd subroutine |
the 6th brace |
the 61st amino acid |
- In some scientific and technical styles, however, write
out numbers between one and ten and two-word fractions
that do not follow an integer:
| three subroutines |
six braces |
61 amino acids |
| 1½ hours |
one-half hour |
|
- If you need to begin a sentence with a number, spell it
out. It is better, however, to reword the sentence, if
possible.
Thirty-two workstations were provided by the
university.
The university provided 32
workstations.
- If one number immediately follows another in a
sentence, spell out the one that can be expressed in
fewer words. Try, however, to express units of measure
in arabic numerals. Another solution is to reword the
sentence.
We then prepared eight 20 ml
samples.
We then prepared 8 samples of
20 ml each.
- Always spell out the pronoun
one:
In protecting the privacy of individuals,
one must always consider all the possible ways
data can be accessed and used.
- Use numerals for dates, time of day, pages, figures,
and notes:
5 August 1994
1 p.m.
page 43
Ref. 6
Figure 43
- Use arabic numerals followed by the percent sign,
(%), to express percentages, except when the number
begins a sentence:
Only 3% of the systems crashed during the
test period.
Three percent of the systems crashed during
the test period.
British and American Formation of Numbers
- Form integers of two to four digits without any punctuation or spacing:
21
412
8024
- Use the period (.) to
indicate the decimal point and use an initial zero
(0) for numbers less than 1.0:
31.3
1.41
0.414
- Form numbers of five digits or more by using a comma (,) to mark off
groups of three digits, starting at the decimal
point:
10,000
12,341
12,341.34
12,432,421
European and International Standards for Formation of Numbers
- Form integers of two to four digits without any
punctuation or spacing:
21
412
8024
- Use the comma (,) to indicate the decimal
point and use an initial zero (0) for numbers
less than 1,0:
31,3
1,41
0,414
- Form numbers of five digits or more by using a period
(.) to mark off groups of three digits,
starting at the decimal point:
10.000
12.341
12.341,34
12.432.421
General Guidelines for Using Numbers in Nontechnical Prose
When using numbers in nonscientific text, spell out numbers less
than one hundred or numbers of any size that begin a sentence.
In addition, spell out round numbers of any size and use arabic
numerals followed by the terms million and billion
to express numbers larger than one million.
seventy-three hours
173 hours
nine hundred thousand
two billion
2.3 million
146 billion
## Numbers ##
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