1. The problem statement, all variables and given/known data Determine if Z[1/5] is a PID (Z is the ring of integers). 2. Relevant equations 3. The attempt at a solution I'm not sure...I tried showing that it isn't by showing that it is not a UFD but that didn't work out well. Maybe there is some way I can show it is a PID by showing it's a Euclidean domain.