I have one of the three numbers: 1, 2, or 3 in my mind. I speak only truth. You can ask me just one question for which I will only reply in yes or no or don't know. What question will you ask from me so that you are able to know the number?

What jumps when it walks and sits when it stands?

In a mathematical quiz, you are asked the following question:

Use three 9s in a mathematical expression without dividing or multiplying to form the number one.

Can you answer the question?

What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?

My thunder comes before the lightning; my lightning comes before clouds; my rain dries all the land it touches. What am I?

When is the top of a mountain similar to a savings account?

An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?

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).

What does Alexander the Great and Winnie the Pooh have in common?

Count the number of triangles in the picture below: