I have teeth but i don't bite. Who Am I ?

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

What can you see in the middle of March and April that you can never see in any other month?

I have holes on the top and bottom. I have holes on my left and on my right. And I have holes in the middle, yet I still hold water. What am I?

If you're 8 feet away from a door and with each move you advance half the distance to the door. How many moves will it take to reach the door?

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

He loves to dance, twist and prance, he shakes his tail, and as a way he sails, wingless he flies into the sky. What is he?

Can anyone tell me a word in the English dictionary which has a silent 'z'?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

Find out a multi-digit number that if multiplied by the number 9 or any of its multiplications products (i.e. 18, 27, 36, 45,..) will result in the multiplication factor repeated (n) number of times.