A. Use the hyphen with the compound numbers twenty-one through ninety-nine, and with fractions used as adjectives.
CORRECT: Sixty-five students constituted a majority.
CORRECT: A two-thirds vote was necessary to carry the measure.
B. Use the hyphen with the prefixes ex, all, and selfand with the suffix elect.
CORRECT: The constitution protects against self-incrimination.
CORRECT: The president-elect was invited to chair the meeting.