. The hyphen is used to hyphenate compound words and between non-continuing numbers, e.g., phone numbers. Ex: twenty-five; 386-9205.
The en dash is used to "connect continuing, or inclusive, numbers -- dates, time, or reference numbers." [Chicago Manual of Style, sec. 5.115]. Ex: May 5th - 7th; open 9 - 5. The em dash is used "to denote a s