There is a box in which distinct numbered balls have been kept. You have to pick two balls randomly from the lot.

If someone is offering you a 2 to 1 odds that the numbers will be relatively prime, for example
If the balls you picked had the numbers 6 and 13, you lose $1.
If the balls you picked had the numbers 5 and 25, you win $2.

Will you accept that bet?

I have nine bottles of wine and one of the nine bottles is poisoned.
I need to find the poisoned bottle with two facts
(1) Poison is deadly, only a sip will cost death
(2) I have two mice to do so.

How should I do it?

I am white when I am dirty, and black when I am clean. What am I?

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?

Why do you find that most of the buildings are deprived of the 13th floor?

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 have a head like a cat and feet like a cat, but I am not a cat. What am I?

What can go up a chimney down, but can’t go down a chimney up?

In a chess board, the queen piece can move horizontally, vertically and diagonally freely. The picture represents the same.Can you place 8 queens on the board in a manner that none of the queens can attack each other?