How can you take 2 from 5 and leave 4?

A woman is sitting in her hotel room and hears a knock at the door. She opens the door to see a man whom she’s never met before. He says, “I’m sorry, I have made a mistake, I thought this was my room.” He then goes down the corridor and into the elevator. The woman goes back into her room and calls security. What made the woman so suspicious of the man?

1 + 9 + 8 = ?
considering, 28 + 8 + 92 = 10

What is more useful when it is broken?

O_er_t_o_

Complete the missing letters of the given word.

Which is the correct shadow of the bird?

What does the below image rebus riddle means ?

What is the centre of gravity?

Here is what you have to do. You have to throw a ball as hard as you can but it must return back to you even if it does not bounce at anything. Also, you have nothing attached to the ball. There is no one on the other end to catch that ball and throw it back at you.

How will you do it?

The doctor advised his patient to take a tablet after every fifteen minutes. He gave him five tablets in total.

How much time will he take to have all the five tablets?