Rational or Not? This Basic Math Question Took Decades to Answer.

In June 1978, the organizers of a large mathematics conference in Marseille, France, announced a last-minute addition to the program. During the lunch hour, the mathematician Roger Apéry would present a proof that one of the most famous numbers in mathematics — “zeta of 3,” or ζ(3), as mathematicians write it — could not be expressed as a fraction of two whole numbers. It was what mathematicians…

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