Just one, but it takes him 20 episodes.
Two, but they have to be very small.
By holding the bulb up to the socket and waiting for the world to revolve around them.
Trick question, anarchists can't change anything.
Only one but he has to have a nurse to tell him which end to screw in.
There's 20 of them!
Okay folks, time to get out of the pool!
20 Episodes and Krillin dies.
Just one. But it takes 20 episodes