Numbers
The General Rule
The rules for expressing numbers are relatively simple and straightforward.
Rule 1
When you’re writing in a nontechnical subject (like English or art), numbers ninety-nine and below should be written out with letters, not numerals.
- There were sixty dogs in the competition.
- I don’t think it’s possible to get 264 bracelets made in one week.
Rule 2
- This study is based on three different ideas
- In this treatment, the steel was heated 18 different times.
Other Rules
Beyond those two general rules, things are a little more tricky.
Rule 3
- Fourteen of the participants could not tell the difference between samples A and B.
- Eighteen hundred and eighty-eight was a very difficult year.
- You may want to revise sentences like this so the number does not come first: “The year 1888 was quite difficult.”
Rule 4
- Two dramatic changes followed: four samples exploded and thirteen lab technicians resigned.
- Sixteen people got 15 points on the test, thirty people got 10 points, and three people got 5 points.
- In this sentence, there are two different “categories” of numbers: those that modify the noun people and those that modify the noun points. You can see that one category is spelled out (people) and the other is in numerals (points). This division helps the reader immediately spot which category the numbers belong to.
Rule 5
Rule 6
- This procedure has a 7% failure rate.
Rule 7
- The judges have to give prizes to at least 25 percent of competitors.
Rule 8
- The metal should then be submerged for precisely 1.3 seconds.
- On average, the procedure costs $25,000.
- The depth to the water at the time of testing was 16.16 feet.
Rule 9
- The sample was heated to 80 °C.
Unlike the abbreviations for Fahrenheit and Celsius, the abbreviation for Kelvin (which refers to an absolute scale of temperature) is not preceded by the degree symbol (i.e., 12 K is correct).
Check out these handy resources related to expressing numbers and numerals in text:
- Technical Writing Best Practices – By the Numbers at http://www.radcomservices.com/technical-writing-best-practices-numbers
- “Using Numbers, Writing Lists” advice from Capital Community College website at http://grammar.ccc.commnet.edu/grammar/numbers.htm