How to crack many Master Lock combinations in eight tries or less Gymnasium locker rooms may never be secure again, thanks to quick and easy hack.

Alongside the mind-boggling brain teaser, he wrote, “Can you still crack the code?” The brain teaser features a lock that can only be opened with a four-digit code.

Imagine a number lock with a three-digit code, and you're given five clues to crack it open. First, one digit is in the correct spot. Second, one digit is right, but it's in the wrong place.