There is a castle with a square moat. It is 2 meters across. You have 2 planks of 1.5 meters in length. You MUST use the planks to cross the moat, there are crocodiles in the water and you are standing on concrete ground. You are trying to get IN to the castle.
How do you cross the moat?
Put one plank across a corner, then balance the second one between the first plank and the ground on the other side of the moat.