### Appendix A:9 Using Numbers Correctly

```Questions about Numbers
• Should you write out the word “twenty-three” or
use the numeral 23?
• Is it fourteen feet or 14 ft. or 14’?
• How would a reader interpret this sentence:
“Assembly requires 3 6 inch boards”?
• Presenting numbers clearly is important in
• Various guidelines exist and may vary from
profession to profession.
• Appendix A.9 presents some standard guidelines
that we’ll use in this class.
Appendix A:9 Using Numbers Correctly
• Use words for zero to nine.
• Use words or numerals for numbers that can be
expressed in one or two words (45 or forty-five).
• Use numerals for numbers that would require
more than two words (127 instead of one
hundred twenty-seven).
• Use numerals in visuals (tables, graphs, etc) and
numbered lists.
• EXCEPTION TO THE FIRST RULE: A document that
contains a significant amount of numerical data,
especially presented as numerals.
• Never begin a sentence with a numeral (spell out
the number or move it in the sentence).
– NOT: The number of Europeans in significant debt is
approximately 1 in 10. 1 in 16 Americans is in
significant debt.
– INSTEAD: The number of Europeans in significant
debt is approximately 1 in 10. However, 1 in 16
Americans is significant debt.
• For very large numbers, combine numerals and
words (100 million, instead of 100, 000, 000).
• Combine numbers and words to prevent
bolts).
• Overall, be consistent.
A test of thirty one control valves at a major
factory revealed more than seventy significant
operating deficiencies, and in another series
of tests conducted on a random sample of 60
control valves, 88 percent exhibited
substandard performance.
In nineteen ninety three, a one hundred and
eighty foot long, three hundred and twenty
eight ton replacement span for the historic
Grosse Island Bridge in Michigan was set in
place in one piece, using the “sinking bridge”
method.
This machine offers a calculated mean time
between failures (MTBF) above one hundred
thousand hours, or more than eleven years if
used twenty-four hours per day, three
hundred and sixty five days per year.
The population of the United States is now
more than two hundred fifty billion.
The temperature in Death Valley often
exceeds one hundred degrees.
```