"Does not compute", and variations of it, is a phrase often uttered by computers, robots, and other artificial intelligences in popular culture. The phrase indicates a type of cognitive dissonance on the part of the machine in question. The expression of the phrase "does not compute" by robots or computers attempting to process emotions, contradictions or paradoxes is frequently satirized in popular culture, often leading to the machine's inaction, malfunction or self-destruction. The phrase was used as a catchphrase by the television show My Living Doll in 1964. It was further popularized in Lost in Space (1965) as a catchphrase often uttered by The Robot character.

The problem of how to hold the result of a computation that is not a number is genuine (for example, 1/0) and represented a problem for early computers that would experience divide-by-zero errors or other mathematical paradoxes that software had not yet been written to deal with, leading to a computer crash. The NaN and related data types were invented to solve this problem.