This is a little riddle that I found out. So, an engineer made a series of switches for a school. Every switch controlled 2 lightbulbs. There are 7 switches, and 8 lightbulbs. At the end of the day, the engineer left one light on, and left. The principal came over, and wants to know how to turn all of them off. Can he do it?
This riddle came from a book called the Mathematical Circle Diaries.
