The Mysterious Planes
Riddle: In front of two planes, there is one. In behind two planes, there is one. In between two planes, there is one. How many planes are there?
Answer: 3 planes. If there are three planes in a row, in front of two, there is one, in behind two, there is one, and in between two, there is one.
Source: https://www.riddles.com/3206
