A mother is 21 years older than her child. In exactly 6 years from now, the mother will be exactly 5 times as old as the child.
Where's the father?

What is black when you buy it, red when you use it, and gray when you throw it away?

John drives to his office at 20km/hr. After reaching the office, he realizes that today is a holiday. He went back at an average speed of 30km/hr. Discounting the time spent in the stoppage what was the average speed of his journey?

One night, Louis and Adam were sitting together. Adam was watching a movie while his wife Louis was reading a mystery book. Suddenly the power went out and Adam decided to go to bed, but strangely Louis kept on reading. There was no artificial light around, so Louis kept on reading. How come?

Solve this riddle by finding the odd one out from the rest.

When Jack was six years old he hammered a nail into his favourite tree to mark his height. Ten years later at age sixteen, Jack returned to see how much higher the nail was. If the tree grew by five centimetres each year, how much higher would the nail be?

There are forty elephants and they have forty-fore heads. How can this be possible?

Alpha is Beta's sister.

Gamma is a Beta mother.

Delta is Gamma's father.

Tango is Delta's mother.

Then,

How is Alpha related to Delta?

Which three-digit number, made of consecutive digits, like 567, is 2 less than a cube and 2 more than a square?

You are in a room that has three switches and a closed door. The switches control three light bulbs on the other side of the door. Once you open the door, you may never touch the switches again. How can you definitively tell which switch is connected to each of the light bulbs?