A brain teaser is a form of puzzle that requires thought to solve. It often requires thinking in unconventional ways with given constraints in mind; sometimes it also involves lateral thinking.

### About *Brain Teasers*

A brain teaser is a form of puzzle that requires thought to solve. It often requires thinking in unconventional ways with given constraints in mind; sometimes it also involves lateral thinking. Logic puzzles and riddles are specific types of brain teasers. One of the earliest known brain teaser enthusiasts was the Greek mathematician Archimedes. He devised mathematical problems for his contemporaries to solve. One can argue about the answers of many brain teasers; in the given example with hens, one might claim that all the eggs in the question were laid in the first day, so the answer would be three. The difficulty of many brain teasers relies on a certain degree of fallacy in human intuitiveness. This is most common in brain teasers relating to conditional probability, because the casual human mind tends to consider absolute probability instead. As a result, controversial discussions emerge from such problems, the most famous probably being the Monty Hall problem.

Contributions by Timwi, Blissey, and Ronz.