Solve the equation in the image by looking at the pattern closely.

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?

Bopanna was working on a murder case when he received a message about the location of the murder weapon.
The message was encrypted as below.

"deb mitciv eht edisni neddih si nopaew redrum ehT"

Tell me the location of the murder weapon.

I have lakes with no water, mountains with no stone and cities with no buildings. What am I?

Make the seating arrangement of 10 children in such a way that there are 5 rows with 4 children in each row.

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

Once upon a time, there was a castle on a square island. The entire island was surrounded by a 14m wide trench. The Romans had wanted to invade the castle and had brought a few wooden planks along with them to facilitate themselves in crossing the moat. The planks were however found to be only 13m long.

The Romans still managed to cross the trench. How did they do it?

Can you move 2 matchsticks to form four equal sized squares.

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?