Generally speaking, we follow the guidelines outlined in the AP Stylebook. In body copy, we prefer to spell out numbers one through nine, and use numerals for numbers 10 and greater. This is true of ordinal numbers, as well. Spell out first to ninth, and capture 10th or greater with numerals.
Sometimes the government writes about very large numbers: millions, billions, even trillions. We express these numbers with a numeral and a word. For example, 1.6 million people. When referring to amounts of money in cents or greater than $1 million, we use numerals followed by words: 5 cents or $2.7 million. For amounts of money less than $1 million, we use the dollar sign: $17.
In titles, subheadings, and interface labels, we use numerals instead of spelling out numbers. For example, 10 digital tech leaders you should know now or 6 ways to incorporate plain-language strategies. We do this to promote ease of reading and scannability — in titles and headings, it’s easier for readers to scan numerals than it is for them to scan written-out numbers.
Use the full, four-digit year. For informal writing, it’s okay to use an abbreviated form. For example, We’re thankful web design isn’t stuck in the ’90s.
In keeping with AP style, we spell out percent in most cases, with a few exceptions. We use the percent sign (%) in these circumstances:
- Tables and in technical or scientific writing. For example: 60% of participants reported experiencing negative side effects.
- Headings and subheadings. For example: Candidate Woof takes 7% lead in the election for best dog.
- Interface labels
- Captions and infographics
We choose to use the percent sign in these cases to improve content’s scannability, allowing readers to digest the content more quickly.