Google filtered applicants with a billboard math puzzle

By 2004 Google was competing for the same engineering graduates every other tech company chased through the same channels — job boards, campus recruiters, referral programs — all of which filtered on credentials and self-presentation rather than the specific quantitative reasoning the job required.

Instead of writing a better job ad, Google put up billboards along Highway 101 in Silicon Valley and near Harvard Square carrying no company name and no explanation: just '{first 10-digit prime found in consecutive digits of e}.com', a pure math problem with nothing to click and no hint it was a job posting.

Solving for the first ten-digit prime in the digits of e led to a website with a second, harder puzzle; only after cracking that second problem did the page reveal it was Google recruiting and invite the solver to submit a resume — the puzzle itself was the entire first-round screen, done before any human read a single application.

Google put an unsigned math puzzle on a billboard, and only those who solved it and the second puzzle it led to were invited to apply, filtering for intrinsic drive.

The puzzle withheld the payoff, so solving it measured intrinsic drive, not eagerness to get hired.

Only someone who already thinks like an engineer would notice and solve an unsigned math puzzle.

The second puzzle raised the bar, ensuring only the most persistent and capable reached the application.

The stunt generated media coverage, attracting even more of the right candidates.

When credentials can't signal the skill you need, put a real, unpaid sample of the work in the applicant's path before the form.

NPR covered the stunt within days; it drew engineers who'd already proven, unpaid, the exact problem-solving Google's interviews tested for. The billboard became one of the most cited recruiting stories in tech, echoed in spirit by defense and intelligence agencies running their own cryptic puzzle recruitment; Google itself later built a persistent version, a hidden coding challenge that appeared inside search results for certain programmer queries.