Easiest Listener Puzzle Ever: The Record Is Already Broken!

And for a numerical puzzle, too. I solved this even more quickly than the puzzle of two weeks ago: during my lunch break, in well under half an hour!

Unless I’m really missing something, there isn’t anything hard about the puzzle at all. The entries in the grid are all two- or three-digit primes whose digits are all odd. It doesn’t take all that long to list them all (there are 54), make sublists of the ones that match the given categories (two-digit twin primes: 11 & 13, 17 & 19, and 71 & 73; three-digit palindromes: 131, 151, 191, 313, 353, 757, 797, 919; and so on), and then try out the not-very-many possible combinations until you find the ones that fit together in the right places in the grid. I was never stuck for what to do next at any point; I was limited more by how fast I could write than how fast I could make deductions.

There is one neat touch: The grid, a 9 × 9 square, turns out to have exactly 54 entries, which means it uses each number exactly once. It’s a nice piece of construction to pack exactly that set of numbers into a perfect square, and have the resulting grid be symmetrical at that. But the clues give way more information than is needed to figure out how to fill the grid.


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