A question about the search for normal subgroups- Conjugacy classes!!!? 1. The problem statement, all variables and given/known data Aut(Z*_24) has Conjugacy classes of order 1, 21, 24, 24, 42 and 56. Show that Aut(Z*_24) is simple. Note: Aut(Z*_24) is sometimes written as U(Z_24) Thanks for any idea or answer... 2. Relevant equations 3. The attempt at a solution I have no idea! At first, why 24 is written 2 times?