A man lives on the fifteenth floor of an apartment building. Every morning he takes the elevator down to the lobby and leaves the building. In the evening, he gets into the elevator, and, if there is someone else in the elevator, or if it was raining that day, he goes back to his floor directly. Otherwise, he goes to the tenth floor and walks up five flights of stairs to his apartment. Can you explain why he does this?

That attorney is my brother, testified the accountant.

But the attorney testified he didn't have a brother.

Who is lying?

Prove that twice of ten is the same as twice of eleven.

I noticed one of the words in the oxford dictionary is spelled incorrectly. What about you?

Can you think of a smallest +ve number such that if we shuffle the digits of the number, the new number becomes double the original number?

Name a key which is hardest to turn.

Is the statement valid that it does not matter how much older a sibling is, eventually the younger one will be half as old as the older one?

Can you count the number of quadrilaterals in the picture below?

What is full of holes but still holds water?

John was drowned by he was not wet. How?