A former CTO shares a simple coding screening question used to filter job applicants. The test presents basic code logic that qualified developers can solve mentally in seconds, while unqualified candidates resort to copy-pasting into interpreters or AI tools. The question includes a hidden character that produces different results when copy-pasted versus solved manually. Results showed 50% of applicants used automated tools, 47% answered correctly, and 3% answered incorrectly, effectively halving the candidate pool requiring deeper review.