Puzzle 101
Kevin wants to go and see his brother, who lives across the valley, and he wants to take his three pets with him, a dog, a cat, and a mouse.
However, the shortest way to his brother's house involves a river crossing, and Kevin only has a very small boat that can carry him and just one of his pets.
He doesn't want to leave the dog alone with the cat, nor does he want to leave the cat alone with the mouse. However, the dog and mouse are great friends.
How can Kevin cross the river to see his brother, and make sure his pets are all happy?
Puzzle 102
Take a normal piece of paper, exactly 0.1 mm thick.
Fold it in half, and then in half again, and again, and again.
Do this a total of 50 times.
How thick would the final paper be (if this could be done)?
Puzzle 103
Painter Pete did such a good job of the housing estate, he was asked to paint the room numbers on all of the doors of the fourth floor of the local hotel.
Pete painted all of the numbers from 400 to 499.
How many times did he paint the number 4?
Puzzle 104
How many squares of any size on this chessboard do not contain a rook?
