# Anthropic uses Claude to formalize Fermat's Last Theorem

Claude completed the first machine-verified proof of Fermat's Last Theorem in Lean, generating over 13 million lines of code.

- The formalization is the largest Lean proof ever written.
- The code machine-verifies Andrew Wiles' 1995 proof along with over 29,000 required supporting theorems.
- Anthropic made the complete formal proof available on GitHub.

## Why it matters

Mathematicians gain automated verification for one of mathematics' cornerstone proofs alongside 29,000 newly formalized lemmas in Lean.

## Sources

- [Anthropic: Anthropic uses Claude to formalize Fermat's Last Theorem](https://x.com/AnthropicAI/status/2095947707605266436)

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Summarized by dstilled on 2026-09-04. https://dstilled.ai/story/7a7158c1-1c12-484e-af4b-4da99d3d74b9