I'd like to know why the answer to "How much did you pay?" is "nothing," rather than "none."
As far as I can tell, the answer to how much/how many should normally be "none," as in:
A: How much water did you give the plants?
B: None, I haven't got around to it yet.
I suspect the reason it should be "How much did you pay?" -> "Nothing." is that if you have a "how much" question with no direct object, the answer should be "nothing," but I'm not sure whether that is correct or not.