At a party, there are five people and a whole round cake lying at the centre of the table. Only four people will make a cut and take their piece and the last one will get the remaining piece on the table. How can they make sure that everyone gets a 1/5th of the piece?

A chess tournament is taking place on knock-out terms (the one who loses the match is out of the game).
(a) If 10 matches are played in total, how many players participated?
(b) If 20 players took part in the tournament, how many matches were played?

Two guards were on duty outside a barracks. One faced up the road to watch for anyone approaching from the North. The other looked down the road to see if anyone approached from the South. Suddenly one of them said to the other, "Why are you smiling?"

How did he know his companion was smiling?

Twenty frogs are sitting on a log floating on the surface of a river. Two of them decide to jump off into the water.

How many frogs are there on the log at this moment?

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

What is always in front of you but can’t be seen?

While sitting in the Car, John suddenly finds that one of the wheels was missing. John noticed that a killer is approaching towards him. John cannot get out of the car.

How will John escape?

You see me once in June, twice in November, and not at all in May. What am I?

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?