What has no start, end, or centre?

Twenty frogs are sitting on a log floating on the surface of a river. Two of them decide to jump off into the water.

How many frogs are there on the log at this moment?

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

When Jack was six years old he hammered a nail into his favourite tree to mark his height. Ten years later at age sixteen, Jack returned to see how much higher the nail was. If the tree grew by five centimetres each year, how much higher would the nail be?

What number do you get when you multiply all of the numbers on a telephone's number pad?

The ages of a father and son add up to 66.
The father's age is the son's age reversed.
How old could they be?
(3 possible solutions).

I was speeding and ran through a stop sign, yet two traffic officers who were there do nothing about it.

why?

A man embarked on a questionnaire game. He kept asking the same question to whomever he found. The answer each time was different.

Can you guess what the question was?

This puzzle is for Harry Potter fans. Do you know why Tom Riddle is called Lord Voldemort?

How could a baby fall out of a twenty-story building onto the ground and live?