I have been reading marketing literature for one client and scientific procedures for another client. I notice differences in style, and I’m particularly interested in the special problems posed for writers of each type of literature when it comes to handling numbers. Scientific writers puzzle over long numbers and line breaks, whether to use a comma or a period to signify a decimal, and spacing between a numeral and a unit of measure. Marketers have to decide whether or not to follow the Associated Press rules regarding spelling out single-digit numbers when numerals can call attention to product advantages. All types of writers seem to have trouble knowing when to use a number and when to use a bullet in a list. Here are a few tips on presenting numbers in your documents:
When to spell out numbers and when to use numerals
The general rule: Use words for numbers zero through nine and use numerals for numbers starting with 10. (The Chicago Manual of Style advocates spelling out numbers zero through 99.) It is acceptable to use all words or all numerals when presenting numbers in a series (Example: 1, 99, and 200)
Scientific publications often use numerals rather than words to represent single-digit numbers. The Council of Science Editors, for example, advocates the consistent use of numerals in text: “This style allows all quantities to be expressed in a similar manner, and because numerals have greater visual distinctiveness than words, it increases the profile of quantities in running text.” To avoid confusion, however, the Council recommends spelling out zero and one.
Scientific publications often use numerals rather than words to represent single-digit numbers. The Council of Science Editors, for example, advocates the consistent use of numerals in text: “This style allows all quantities to be expressed in a similar manner, and because numerals have greater visual distinctiveness than words, it increases the profile of quantities in running text.” To avoid confusion, however, the Council recommends spelling out zero and one.
Other rules:
- Use words for numbers that begin a sentence, unless the sentence begins with a calendar year or an organization or product name that begins with a number.
- When two numbers are next to each other, spell one of them (Example: 28 twelve-foot boards).
- Use words in quotes and dialog.
- Use words for simple fractions (Example: one-half).
- Use numerals with other fractions, except at the beginning of a sentence.
- Use numerals to show the age of a person.
Using numbers in lists
Bullets are ubiquitous in presentation materials, probably because bulleted items are built into presentation software. Lists are great ways to present material that audiences scan. They are great for visually organizing training and technical material for easy comprehension. But be sure that you use the appropriate type of list to present the material.
When should you use numbers in a list? When you need to to show order:
- To describe procedures and processes. Most how-to-do-it or how-it-works text benefits when you number steps that must be performed in a certain order.
- To show order of importance.
Use bullets when order is not important or when all items have the same weight.
A note about lists
Bullets and numbers signify that you are presenting lists, and a list contains more than one item. Even in presentations, I avoid using a bullet with a single item.