What is the next number in this series?

4,12,84,3612....

A 3 digit number is such that it's unit digit is equal to the product of the other two digits which are prime. Also, the difference between it's reverse and itself is 396.

What is the sum of the three digits?

Where do you go to learn how to make ice cream?

You are in a room with no metal objects except for two iron rods. Only one of them is a magnet.
How can you identify which one is a magnet?

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.

Our product and our sum always give the same answer. Who are we?

A woman lives in a skyscraper thirty-six floors high and is served by several elevators which stop at each floor going up and down. Each morning she leaves her apartment and goes to one of the elevators. Whichever one she takes is three times more likely to be going up than down. Why?

In the image given, you can find several triangles. Can you count them all?

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

What always comes into a house through the keyhole?