A 358-year-old math problem was solved in a professor's attic

Pierre de Fermat claimed in 1637 to have a proof too large for a margin to hold, then never wrote it down. Andrew Wiles worked in near-total secrecy for seven years to prove Fermat's Last Theorem, announcing it in 1993 — only for reviewers to find a gap in the logic. He closed the gap with former student Richard Taylor, and the finished 129-page proof was published in 1995.

— Andrew Wiles, Modular Elliptic Curves and Fermat's Last Theorem — Annals of Mathematics, 1995