Does thirty one have a hyphen? You should always hyphenate numbers when youare describing compound numbers between 21 and 99 (except 30, 40, 50, 60, 70, 80 and 90). A compound number is any number that consists of two words; for example, eighty-eight, twenty-two, forty-nine. ...
An en dash (–) is a punctuation mark that's longer than a hyphen but shorter than an em dash. It's used primarily to indicate ranges of numbers, like “pages 10–20,” or to link related items, like “the New York–London flight.” It's also sometimes used to replace “to” or...