James Stanley

Prime Combination

Sun 5 February 2023
Tagged: puzzle

You come across a 5-digit combination padlock. The combination is 10723. The padlock is currently showing 00001. If the combination is ever set to a number that is not prime, it resets to 00001 immediately, so every intermediate state from 00001 to 10723 also must be prime. How do you input the combination?

I have posted a solution and some analysis.

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