Why do people go to bed?

Count the squares in the matchstick puzzle below?

Identify the hidden meaning behind this picture?

Name a key which is hardest to turn.

Two fathers and two sons decided to go to a shop and buy some sweets upon reaching. Each of them bought 1 kg of sweet. All of them returned home after some time and found out that they had 3kg of sweets with them.

They did not eat the sweets in the way, nor threw or lose anything. Then, how can this be possible?

Transform the word THINK into BRAIN while changing only one letter at a time in a manner that each of the word in the process is a real word!!!

In four steps you need to move the word 'cold' From 'warm' by replacing one alphabet at a time such that every word formed at each step is acceptable in English Dictionary.

A man dies of old age on his 25 birthday. How is this possible?

Is the statement valid that it does not matter how much older a sibling is, eventually the younger one will be half as old as the older one?

If you're 8 feet away from a door and with each move you advance half the distance to the door. How many moves will it take to reach the door?