Can you find out the missing number in the grid?

I speak without a mouth, and hear without ears. I have no-body, but I come alive with the wind. What am I?

Count the number of triangles in the given picture.

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?

There are three light switches outside a room. One of the switches is connected to a light bulb inside the room.
Each of the three switches can be either 'ON' or 'OFF'.

You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)

Your task is to then determine which switch controls the bulb?

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?

It is a six-letter word.
The first four letters are me.
The second and last letters are the same.
The fourth second and last letter is payment.

Who is it?

If you’ve got me, you want to share me; if you share me, you haven’t kept me. What am I?

You have a three-gallon and a five-gallon measuring device. You wish to measure out four gallons.

What is the largest amount of money that you can possess in change and still if someone asks you for a dollar, you won't be able to give?