Math Dog -Riddles

Q: Why did the dog's owner think his dog was a great mathematician?
A: When he asked the dog what six minus six was, the dog said nothing.

Heads and Tails

Q: How is a dog's tail like the center of a tree?
A: It's furthest from the bark!

Dog Food

Q: What is the only kind of dog you can eat?
A:  A hot dog!