English Grammar for the Utterly Confused - Laurie Rozakis 2003
Hyphens
Chapter 10 Punctuation
Part 4 A Writers Tools
A hyphen (-) is smaller than a dash. Use a hyphen to show a break in words. Traditionally, a hyphen was used to show a word break at the end of a line. However, modern computer software has virtually eliminated this use of the hyphen.
1. Use a hyphen in certain compound nouns.
pint-sized great-grandmother
2. Use hyphens in written-out fractions and in written-out compound numbers from twenty- one to ninety-nine.
one-half
fifty-five