Take 9 from 6, 10 from 9, 50 from 40, and leave 6.

How Come ??

There is a box full of marbles,
all but two are blue,
all but two are green,
and all but two are red.

How many marbles are in the box?

Find the next number in the series below

21 32 54 87 131 ?

When we see 2 but call 10?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

You have two strings whose only known property is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different. How do you measure 45 minutes?

What Time Should the last watch show in the below figure?

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 the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?

Can you find out the number of the parking space in which the car is parked?