Move four matchsticks to the below square to form three squares?

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?

What occurs twice in a week, once in a year but never in a day?

Can you discover the missing number in this series?

37, 10, 82
29, 11, 47
96, 15, 87
42, ?, 15

Can you solve below mathematical equation?

2^1234 - 2^1233

Can you complete the sequence?

192, 021, 222, 324, 252, 627, 2__, 9__?

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

How many times can you subtract the number two from the number fifty?

Jim and Sarah are in a long-distance relationship. Jim buys an engagement ring for Sarah and wants to mail it to her. Unfortunately, the only way to ensure the ring will be received is to place a lock on the package. Jim has locks and Sarah has locks, but neither has keys for each other’s locks. How can they make sure the ring isn’t stolen?

I am quite hot but become too cold if you remove the first two letters. What am I?