Here's an easy puzzle that should take you only five minutes to solve, inspired by my hallway. Most intuitive answer get the mark:
Six switches control the same light bulb in a multiway switching scheme. That way, changing the state of any switches changes the state of the light bulb.
In the beginning, all six switches are at the UP position and the light is on. How do you turn the light off and have all six switches at the DOWN position?