Percentage

Percent: In APA and CSE, use 18%. In MLA, use eighteen percent (in contexts with few numbers if the percentage can be expressed as three or fewer words) or 18% (in contexts with many numbers). AP mixes numerals with the word "percent" (18 percent). In Chicago and Turabian, if the document is in the humanities, use 18 percent; if the document is in the hard or social sciences, use 18%.