By including only four matchsticks in below picture, you have to make "Four Triangles And Two Squares"

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

If 1+9+8=1, what is 2+8+9?

I have teeth but i don't bite. Who Am I ?

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

The sum of a mother, her baby and her dog's weight is 170 Kg. How much does the baby weigh if the mother weighs 100 kg more than the combined weight of the baby and the dog, and the dog weighs 60 per cent less than the baby?

What has a ring but no finger?

What makes this number unique: 8,549,176,320?

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?