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 Lateral thinking is a manner of solving problems using an indirect and creative approach via reasoning that is not immediately obvious. It involves ideas that may not be obtainable using only traditional step-by-step logic. The term was first u ...

Logic puzzle A logic puzzle is a puzzle deriving from the mathematical field of deduction. History The logic puzzle was first produced by Charles Lutwidge Dodgson, who is better known under his pen name Lewis Carroll, the author of ''Alice's Adventures in W ...

s and

riddle A riddle is a statement, question or phrase having a double or veiled meaning, put forth as a puzzle to be solved. Riddles are of two types: ''enigmas'', which are problems generally expressed in metaphorical or allegorical language that requ ...

s are specific types of brain teasers. One of the earliest known brain teaser enthusiasts was the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...

Archimedes. He devised mathematical problems for his contemporaries to solve.

Example

:Q: ''If three hens lay three eggs in three days, how many eggs does a (statistical) hen lay in one day?'' :A1: ''One third.'' (Note: 3 hens = 3 eggs / 3 days → 3 hens = (3 / 3) (eggs / days) → 1 hen = (1 / 3) (egg / days)) :A2: ''Zero or one'' (it's hard to lay a third of an egg). 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. :Q: ''Mary's father has five daughters: 1. Nana, 2. Nene, 3. Nini, 4. Nono. What is the name of the fifth daughter?'' :A: ''Mary. The first four daughters all have names with the first 4 vowels, so if someone does not think about the question, they may say the name with the fifth vowel, Nunu. The answer was given at the beginning of the question (ie, Mary's father has five...) :Q: ''What appears once in a minute, twice in a moment, but never in a thousand years?'' :A: The letter "M". :Q: ''I am the beginning of the end, the beginning of eternity, and the end of all time?'' :A: The letter "E".

Intuition

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 In probability theory, conditional probability is a measure of the probability of an event occurring, given that another event (by assumption, presumption, assertion or evidence) has already occurred. This particular method relies on event B occu ...

, because the causal human mind tends to consider absolute probability instead. As a result, controversial discussions emerge from such problems. One of the famous brain teasers is the Monty Hall problem. Another (simpler) example of such a brain teaser is the

Boy or Girl paradox The Boy or Girl paradox surrounds a set of questions in probability theory, which are also known as The Two Child Problem, Mr. Smith's Children and the Mrs. Smith Problem. The initial formulation of the question dates back to at least 1959, when&nb ...

References

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Example

Intuition

See also

References