Just one, but it takes him 20 episodes.
One....Two...One, Two...
Seven. One to change it, two to take pictures, and four to make t-shirts for the event.
Probably one but you can't generalise.
Vending machines.
28 29's
20 "Twenty-*one*. She got the last one when she wished for legs."
20 Episodes and Krillin dies.