My friend Cacher_Roy dropped by a few weeks ago, and saw that I was working on a Sudoku puzzle. I was surprised by his reaction:
Roy: You shouldn't do Sudokus; they're evil!
Me: You mean because of all the time people spend solving them, when they could be out finding caches?
Roy: Well, that too, but I was thinking of their cruelty to digits.
Me: Huh?
Roy: Think about it. In a Sudoku puzzle you can't have two of the same digit in any row, column, or 3x3 box. But digits like to be around other digits like themselves. Surely you've heard the old saying "2's enjoy company, 3's like being in a crowd.".
Me: I don't think that's the way I've heard it.
Roy: Oh? Well anyway they do. That's why you see numbers with repeated digits so often. Like 999, the emergency phone number in the UK. Or 555, the telephone prefix used in movies and TV shows. Or the old TV series "Route 66", "77 Sunset Strip", and "Room 222". Or movies like "Ocean's 11" and "Call Northside 777". Or the songs "99" by Toto and "99 Luftballons" by Nena.
Me: Or Maxwell Smart's wife, Agent 99. But I figured those numbers were chosen to make them easier to remember.
Roy: That seems pretty far-fetched. No, I'm sure it's because the digits prefer it that way. Anyway, since Sudokus force digits to be separated from their kin, they're evil. Everyone should just stop doing them.
Me: Hmm, I don't think that's going to happen. But maybe we can come up with a different sort of puzzle that will balance things out a bit. Suppose that, instead of avoiding duplicate digits in the rows, columns, and boxes, we require them? We say that if a digit occurs at all, it must occur at least twice.
Roy: I'm sure the digits would appreciate that. But can you make a good puzzle like that?
Me: I'll have to get back to you on that.
So I spent a few weeks trying to create such a puzzle, first by hand, and then with the help of a computer program. Eventually my program produced hundreds of puzzles and I solved a bunch of them. Some were too easy; the most obvious solving methods led to a complete solution. Others were so difficult that I gave up; I couldn't see any way to solve them without printing out dozens of copies of the puzzle and trying different possibilities. But finally I found some that were easy enough to solve with just one copy of the grid, but challenging enough to give a sense of satisfaction upon completion.
I called Cacher_Roy to let him know what I'd come up with:
Me: I'm not sure I accept your "cruelty to digits" idea, but I did manage to create some puzzles that I enjoyed solving.
Roy: Great! Can I try one?
Me: Sorry, you'll have to wait until my new cache is published.
And now it is. Put a digit from 1 to 9 in each square in the grid, so that in every row, column, and 3x3 box formed by the thick lines, no digit occurs exactly once. If a digit appears at all, then it must occur at least twice. I've filled in some squares to get you started.
Once you've solved the puzzle, use the digits from the squares labelled A through F to form the final coordinates of the cache:
N 40 46.ABC W 124 07.DEF
If you think you've figured out the coordinates, you can check them with certitude:
You can also see who else has solved the puzzle. Note: You can remain anonymous if you want to; incorrect guesses are always anonymous. (Puzzle makers, you can create your own certitude links here.)
There's a dollar for the FTF.
Congratulations to the first certified solvers, rickrich and gallaghd, and the first finder, Doc_musketeers.
On 4/12/2019, this puzzle was
