Claude formalized Fermat's Last Theorem in 11 days against a human project funded through 2029

Thirteen million lines in eleven days works out to about 1.18 million lines a day, close to 49,000 an hour, sustained, with Lean rather than a person checking each one ^[2][3][16]. Divide those lines by the more than 30,000 supporting theorems Anthropic says the agents proved and the average result runs about 433 lines ^[15][18], which gives the shape of the job: thousands of small results stacked, rather than one long argument. Checking is the expensive half of mathematics, since finding a single broken link inside a hundred pages of dense argument can cost other mathematicians years ^[14], and a 1908 German prize for a valid proof of this same theorem drew 621 wrong submissions in its first year ^[13].

The disclosure's clearest number is also its least flattering. Roughly 7% of the lines in the finished proof are false starts from the early phase, when the agents kept losing track of what they had already proven and stopped collaborating ^[8], which is about 910,000 lines of dead work carried into the artifact ^[17]. Coordination broke down first, and Prove2Me fixed it: a tool from Tianyi Peng's Columbia team that handed every agent the same live to-do list, reorganized files so Lean could check them faster, and kept plain-English notes so one agent could reuse another's result ^[9][1]. The eleven days therefore sit on top of a human-built shared-state layer; the scarce input in this run was that coordination layer itself, not raw model access.

Which is where the capital-allocation reading gets thin. Anthropic's post is dated September 4, 2026 and puts completion in the previous month ^[10]; it quantifies consumption as billions of tokens and no dollars, on a research model it says is roughly comparable to the Claude Fable 5.1 version it later shipped ^[15]. The account does not say what share of Kevin Buzzard's 86-page outline the proof covers, nor whether it drew on the Imperial project's existing Lean library ^[12][5]. Buzzard's funding is committed through 2029 ^[5], and eleven days is about 0.6% of that window ^[20], a striking ratio measured in time, not dollars.

My read, with the counter-thesis beside it: the transferable capability is throughput on work where a checker returns a verdict at every step, and a verifier like Lean is the rarer asset here, not the agent. The counter is that Prove2Me is a to-do list and a file organizer rather than a new model ^[9], so if that scaffolding ports cheaply, any domain with a compiler or a test suite inherits the same curve. A third path runs through the review itself: Buzzard is the one named mathematician who has confirmed the proof reduces to math's most basic logical rules ^[4], and Wiles's 1993 announcement survived three lectures before a reviewer found the hole in it ^[6].

Note also the gap between the framing and the event. Decrypt's headline calls this a 350-year-old problem solved by AI ^[11] while its own text counts 358 years from Fermat's 1637 margin note ^[7] and credits Wiles with the proof, corrected with Richard Taylor and published across 129 pages in May 1995 ^[6]; what Claude did was translate that argument into a language a machine can check ^[2]. For scale on that translation, the formal version carries roughly 100,000 lines per published page of Wiles ^[19]. Until someone publishes the token bill, eleven days is a quote with the price torn off.