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?

Can you count the number of triangles in the given picture?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

Can you make four (4) nines (9) equal 100?

What number comes next in this sequence:
7 8 5 5 3 4 4 _

Until it is measured, not known. Yet how you miss it when it has gone. What is it?

Can you find the key in the picture below?

Today is John's birthday.
A year ago, John had five candles and he lit all the candles except the one at the last.
Now he is going to light all the candles.

How old is John Today?

(He is not five today.....)

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

what does the below rebus means?