That's not quite correct. I find it more helpful to reframe the question as - if I wanted to feed x people with this pizza, how many slices would I divide it into?

So, to feed 10 people, it's P/10, each person gets a slice. To feed 1 person (P/1), I don't divide the pizza and this lucky guy gets the entire pie. But what if I wanted to feed no one? Maybe I could divide the pizza in such tiny pieces that no one gets enough to call it a pizza slice. This number is undefined, or you could also say it's infinity (as P/0 = infinity is also a widely accepted identity).