NEW RIDDLES

Why was the maths book sad and worried?

Use the 10 letters ACDEHIJLNP to spell out the names of four countries. Each name must be five letters long, and the four countries must be neighbours.

A magician promises that he can throw a ball as hard as he can and have it stop, change direction, and come back to him. He claims he can do it without the ball bouncing off of anything, the ball being tied to anything, or the use of magnets. How is this possible?

A man skips happily into a bar. He orders a Coke. The waiter does not serve him, but he says... "Sorry, we do not serve mushrooms here." Why won't the waiter serve him?

I am a single digit number. When you add myself to me, you will get the answer to me by the addition symbol sideways, turned up-side-down. What number am I?