Originally Posted by

**sirellwood** Hi all,

Brief intro to what im talking about....

If n $\displaystyle \geq$ 2 is an integer, then Zn* denotes the set of invertible elements in the ring Zn. That is, it denotes the numbers in {1,2....n-1} which are coprime to n. The set Zn* is a group under multiplication modulo n.

Does anyone know how to determine whether or not these groups are cyclic?: Z8*, Z9*, Z10*, Z12*

Maybe someone can walk me through the first couple and i can try the others for myself!

Thanks!