What is full of holes but still holds water?

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?

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

A boy was locked in a room by some robbers. All that is in the room is a piano, a calendar, and a bed. The room is locked from the outside. What does he eat, drink, and how does he escape and get out?

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?

Find the number of squares in the below picture

There is something which is always coming but never arrives?

Replace the letters of words with a number so that the below equation holds true

BASE +
BALL
---------
GAMES
----------

See the given image carefully. What you have to do is move the blue checkers in the position of the black checkers and vice versa. You are only allowed to move the checker to an adjacent empty space. Do it in the least possible moves.

What am I?