Hold to these rules when using AP Style Fractions in your writing.
Spell out amounts less than 1 in stories, using hyphens between the words. For example,
- This recipe calls for two-thirds of a cup.
- Are you sure? I thought I had read four-fifths.
- I need a size twenty-seven-sixty-fourths drill bit.
Use figures for precise amounts larger than 1, converting to decimals whenever practical.
When using fractional characters, you should remember that most newspaper type fonts can set only 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, and 7/8 as one unit. For mixed numbers, use 1 1/2, 2 5/8, etc., with a full space between the whole number and the fraction.
Other fractions require a hyphen and individual figures, with a space between the whole number and the fraction. For example,
- 1 3-16
- 2 1-3
- 5 9-10
In tabular material, use figures exclusively, converting to decimals if the amounts involve extensive use of fractions that cannot be expressed as a single character.
See also AP Style Numerals and AP Style Percent.