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?

I am white when I am dirty, and black when I am clean. What am I?

Four people need to cross a rickety bridge at night. Unfortunately, they have only one torch and the bridge is too dangerous to cross without one. The bridge is only strong enough to support two people at a time. Not all people take the same time to cross the bridge. Times for each person: 1 min, 2 mins, 7 mins and 10 mins. What is the shortest time needed for all four of them to cross the bridge?

I am never scared but became petrified and can’t live in a house but would die to make one. What am I?

I have branches, but no fruit, trunk or leaves. What am I?

What has many keys but can’t open a single lock?

The chance of Mr John winning the lottery is 10%. All participants lined up and Mr John is 4th in the row. The first three participants lose the lottery.

What is the chance of Mr John now?

If you read clockwise, you can form a word by inserting three missing letters in the picture given below. Can you do it?

What has 13 hearts but no other organs?

John’s parents have three sons: Snap, Crackle, and what’s the name of the third son?