@andrewt This is neat but I don't know which 5-digit numbers are / are not primes so it degenerated into a lot of guess-and-check for me.
@andrewt @jsiehler I think it's just on the verge of playable. Like @jsiehler said, it's hard to know which 5 digit numbers are primes, so it devolves into a lot of failed guesses pretty quickly.
I'm sure there's a modification or two that could be made to improve it, but I'm just not sure what they are.