Fun Fact: Google Recruited with an Anonymous Billboard
Abstract
In July 2004 a billboard appeared on Highway 101 in Silicon Valley (and in Harvard Square) reading only “{first 10-digit prime found in consecutive digits of e}.com”. No company name, no explanation. The answer, 7427466391, led to a website with a second, harder problem, which finally unlocked a Google recruiting page. The campaign was a self-selecting filter: only people who could solve it ever found out who was hiring.
The Puzzle Chain
The first stage asks for the first ten-digit prime that appears in the decimal expansion of e (2.718281828…). Brute force works fine if you think to write the program: slide a ten-digit window along the digits of e and test each for primality. The answer is 7427466391, and typing 7427466391.com into a browser delivered the second stage.
That page congratulated the visitor on reaching “level 2” and posed a sequence puzzle: given f(1) = 7182818284, f(2) = 8182845904, f(3) = 8747135266, f(4) = 7427466391, find f(5). The values are the ten-digit substrings of e whose digits sum to 49, in order of appearance; the next one is 5966290435. That number, used as a password on a linked login, opened a page at Google Labs which admitted the whole thing was a hiring funnel and invited the solver to send a résumé, on the logic that “what you’re looking for, we’re looking for too.”
The Tradition It Joined
The stunt is the private-sector version of a much older trick: the Daily Telegraph’s January 1942 crossword speed contest, whose winners were quietly recruited to Bletchley Park (see Recruiting by Puzzle). Google’s twist was anonymity as branding. The billboard’s silence about its sponsor was the point: it flattered exactly the audience it wanted, and everyone else drove past.