What has no start, end, or centre?

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?

A deaf and mute man goes to the train station. Tickets for the train are 50 cents each. The man goes to the ticket booth and hands the man inside just a dollar. The man in the booth hands him two tickets.

How did the man in the booth know to give him two tickets without even looking at him?

If six children and two dogs were under an umbrella, how come none of them got wet?

Speaking of rivers, a man calls his dog from the opposite side of the river. The dog crosses the river without getting wet, and without using a bridge or boat. How?

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

What is the centre of gravity?

Can you count the number of triangles inside a triangle?

By using 'because' continuously three times, can you make an English statement ?

What is both possible and impossible at the same time?