Here's a larger version of my last puzzle, now in full 9x9 glory! If you’re new to prime numbers you only need to know that the first seven primes are 2, 3, 5, 7, 11, 13, and 17 to try it.
The numbers in this puzzle reveal the sum of the entries in adjacent cells only when exactly one of those numbers is prime. The diamonds reveal that either both or neither number is prime.
Solution and PDF version at: https://quadratablog.blogspot.com/2020/ ... mdoku.html
