The proof of Fermat's Last Theorem has been called the mathematical event of the century; this popular account puts the discovery in perspective for non-mathematicians. As one of the producers of the BBC Horizons show on how the 300-year-old puzzle was solved, Singh had ample opportunity to interview Andrew Wiles, the Princeton professor who made the historic breakthrough. As a schoolboy in England, Wiles stumbled across a popular account of Fermat's puzzle: the assertion that no pair of numbers raised to a power higher than two can add up to a third number raised to the same power. Singh traces the roots of the problem in ancient geometry, from the school of Pythagoras (whose famous theorem is clearly its inspiration) up to the flowering of mathematics in the Renaissance, when Fermat, a French judge who dabbled in number theory, stated the problem and claimed to have found a proof of it. Generations of the finest mathematicians failed to corroborate his claim. Singh gives a colorful and generally easy-to-follow summary of much of the mathematical theory that was generated in attempts to prove Fermat's conjecture. Finally, in the 1950s, two Japanese mathematicians came up with a conjecture concerning elliptical equations that, at the time, seemed to have nothing to do with Fermat's problem. But it was the Taniyama-Shimuru conjecture that gave Wiles the opening to solve the problem after working in isolation for seven years. He announced his proof at a famous mathematical congress in Cambridge, England--a truly great moment in mathematical history. Then a flaw in the proof presented itself- -and Wiles went back to work for over a year to patch it up. Finally he succeeded, and the greatest problem in mathematical history was laid to rest. A good overview of one of the great intellectual puzzles of modern history. (photos and line drawings)