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?

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?

Find the number of squares in the below picture

Can you name some countries which do not have the alphabet 'A' in them?

Can you place six X (crosses) in below board without making three in a row in any way ?

Can you find a number that lies one third of the distance between 1/3 and 2/3?

what does this below rebus represent identXQQQQQME

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

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

What three numbers, none of which is zero, give the same result whether they’re added or multiplied?