Matchstick puzzle

A matchstick puzzle is a rearrangement puzzle in which a number of matchsticks are arranged into shapes, patterns, or numbers, and the solver is asked to move a fixed number of the matchsticks to reach a different, specified arrangement. Many matchstick puzzles present a false mathematical equation built from Roman or Arabic numerals rendered in a seven-segment style, and the task is to move one or more sticks so the equation becomes true. Other variants rearrange crude matchstick pictures into a new picture, or ask the solver to build a shape from scratch under strict stick-count rules. Some puzzles reward lateral thinking rather than direct rearrangement, such as converting a number into a mathematical symbol instead of another number. A frequently cited example challenges the solver to build four equilateral triangles using only six matches, which is only possible by lifting the matches off the flat surface and constructing a three-dimensional tetrahedron. Matchstick puzzles have long been a staple of recreational mathematics columns and puzzle books because they need no equipment beyond a box of matches or matchsticks and reward geometric insight over calculation.