If eleven plus two equals one, what does nine plus five equal?

Sherlock Holmes was challenged to make a pre-drawn line smaller without erasing it. He did it in fractions of seconds. How?

There is one four-digit whole number n, such that the last four digits of n2 are the original number n

At my favorite fruit stand,
an orange costs 18,
a pineapple costs 27,
and a grape costs 15.
Using the same logic, can you tell how much a mango costs?

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

Wednesday, Steve and Pam go to a restaurant to eat lunch. After eating lunch, they pay the bill. But Steve and Pam do not pay the bill. So…who does?

What is the fastest way to double your money?

Eight of us go fourth, not back, to protect our king from an attack. What are we?

You need to remove two matchsticks to make the below equation true. Can you do it ?

A girl was sitting in her hotel room when she heard a knock on the door. She opened the door and found that a man was standing outside.
The man said, "Oh! I am really sorry, I thought this was my room."
He then walked through the corridor to the elevator. The girl did not know the man. She closed her door and called security asking them to apprehend the man.
What made her suspicious of that man? He might have been genuinely mistaken.