John is the son of Jacob.
So,
Jacob is the_____of John's father?

In the given figure, move three matchsticks so that the resulting figure contains two rectangles.

10 people came into a hotel with 9 rooms and each guest wanted his own room. The bellboy solved this problem.
He asked the tenth guest to wait for a little with the first guest in room number 1. So in the first room, there were two people. The bellboy took the third guest to room number 2, the fourth to number 3, ..., and the ninth guest to room number 8. Then he returned to room number 1 and took the tenth guest to room number 9, still vacant.
How can everybody have his own room?

Find The Next Number In The Sequence

30 10 15 13 0 16 -15 ?

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?

In a science lab, a petri dish hosts a healthy colony of yeast for an experiment. Now every minute, all the yeast cells divide into two. At noon, there was just a single cell of yeast and at 1:22, the Petri dish was half full. Can you calculate when the dish will be full of yeast?

Forwards I am heavy, backward I am not. What am I?

When 99 is considered higher than 100?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

One day, John and his friends were playing around. Jacob hit something with a Pin and it popped. John's dad came into the room that very moment, but he wasn't mad. In fact, he was smiling. What did Jacob hit?