What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

How can you make number one disappear by adding something to it?

How many bananas can you eat if your stomach is empty?

There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

What always comes into a house through the keyhole?

A cricket has 6 legs, a squirrel has 4 legs and a spider has 8 legs.

In a local zoo, it was found that the total number of legs is 612. Also, there are equal number of each of the above animals/insects.

Can you find out how many animals are there in the zoo?

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?

I am a normal creature, but I have five hands. I can even have more but even then I will be considered normal.

Who am I?

A man in a car saw a Golden Door, Silver Door and a Bronze Door. What door did he open first?

I make two people out of one. What am I?