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?

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

Find the next number in the series.
1 10 24 43 67 ?

Take away my first letter, then take away my second letter. Then take away the rest of my letters, yet I remain the same. What am I?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

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?

Can you find the thief by just looking at the picture below?

Can you spot the man between the coffee bean in the picture below ?

I look at you, you look at me, I raise my right, you raise your left. What am I?

Find the number of squares in the below-given picture.