Brain teaser

A puzzle or problem designed to challenge reasoning, lateral thinking, or ingenuity, often through an unexpected interpretation or constraint.

Lateral thinking: A problem-solving approach that seeks solutions by changing perspective or challenging assumptions. Many teasers reward abandoning the most obvious interpretation.
Monty Hall problem: A probability puzzle in which switching doors after a host reveals a goat improves the chance of winning. Its counterintuitive answer makes probability assumptions visible.
Constraint satisfaction problem: A problem defined by variables, possible values, and constraints that restrict valid combinations. Many teasers can be formalized as finding an assignment that satisfies every rule.
Cognitive psychology: The study of mental processes such as perception, memory, reasoning, and language. Researchers use puzzle solving to investigate how people think and make errors.
Abductive reasoning: Inference that identifies the best explanation for incomplete observations. Some teasers ask solvers to infer a hidden situation from sparse clues.
Nine-dot problem: A puzzle asking for four straight lines that pass through nine dots without lifting the pen. Its solution requires questioning an unstated boundary assumption.
Ambiguity: The property of language or information that permits more than one interpretation. A carefully chosen wording can support a misleading reading alongside the intended one.
Mathematical recreation: The use of mathematical ideas in puzzles, games, and other leisure activities. Many teasers make mathematical structure accessible through a compact challenge.
Deductive reasoning: Reasoning that derives conclusions that must follow from stated premises. Logic-based teasers test whether conclusions follow from their given conditions.
River crossing puzzle: A family of puzzles in which people, animals, or objects must cross a river under constraints. Its changing constraints require planning a valid sequence of moves.

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Mathematical puzzleCompared with: Some brain teasers rely more on wordplay or reframing than mathematics.