The centre of the third figure is empty. What digit should fit inside?

Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

I know a ten-letter word in the English language which can be typed using only the top rows of the computer keyboard.

There was a man he lives in a hotel each morning he presses the first floor button each evening if there is a person in the elevator he asks him to press the 10 floor button if there is no one in the elevator he takes the stairs why.

You can see three almost identical images below. Can you spot the odd one out from them?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

How can a man go eight days without sleep?

There are two guys standing face to face in a room. On a wall, there is a clock. One of those is a prophet. He tells the other guy that he will be stabbed in the back in five minutes.

Shocked to hear that, the other guy stares at the clock. Just after the five minutes, he is stabbed on the back. Can you tell what happened?

I am not alive, but I grow; I don't have lungs, but I need air; I don't have a mouth, but water kills me. What am I?

John, Jack and Jill are in a desert. John doesn't like Jill and hence decides to murder him. He poisons the water supply of Jill. Since it is a desert area, Jill must drink or he will die of thirst.

Jack does not know of the actions of John and also decides to murder Jill. To succeed in his ill motives, he removes the water supply of Jill so he dies of thirst.

Jill dies due to thirst. Who murdered Jill?