Use hyphens to create phrasal adjectives by connecting two or more words.
- He enrolled in a two-week course.
- It’s a fast-growing trend.
- Ashe looked at us with an I’m-not-sure expression.
Most phrasal adjectives are not hyphenated after a noun.
- The course was two weeks.
- The trend was fast growing.
Hyphenate two-word numbers under one hundred.
- Twenty-two.
- Ninety-nine.
Hyphenate fractions.
- One-half.
- Two-tenths.