# How to Trap Your Moderator

You have locked your least favorite moderator behind a 27x27 Sudoku...
Now you regret, but you have forgotten how to solve the puzzle...

CSV version:

,  , 1,  ,  ,  ,  ,  ,  , 5,  ,  ,  ,  ,  ,  ,  ,  ,  , 7,  ,  ,  ,  , 6, 1,
6,  ,  ,  , 5,  ,  ,  ,  , 2,  , 8, 9,  ,  ,  ,  , 2,  , 4,  , 9,  ,  , 7,  , 9
2,  , 9,  , 7, 6, 3,  ,  , 4,  ,  ,  , 3,  , 4,  ,  ,  ,  , 5,  ,  ,  , 4,  , 8
,  , 8,  ,  ,  ,  ,  ,  ,  ,  ,  ,  , 4,  , 6,  ,  ,  , 6,  ,  ,  , 7,  , 4, 5
,  , 4,  , 7,  ,  , 6, 1,  ,  , 5,  , 6,  , 8, 9,  , 2,  ,  , 8,  ,  ,  ,  , 2
,  ,  ,  , 1, 2, 4, 3,  ,  , 6, 1,  ,  ,  ,  ,  ,  ,  ,  ,  , 1,  , 4, 6,  ,
, 8,  ,  , 2,  , 5,  , 8,  , 5, 3,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,
,  ,  ,  ,  ,  ,  ,  ,  ,  , 1, 4,  , 7,  ,  ,  ,  , 4,  ,  ,  , 6,  , 3,  ,
, 5,  ,  ,  ,  ,  , 4,  ,  ,  ,  ,  , 8,  , 1,  , 5, 3,  ,  ,  , 7,  ,  ,  , 2
, 7, 5, 8, 3, 9,  , 4,  ,  ,  , 9,  , 4,  ,  , 7,  , 1,  ,  ,  ,  , 6,  , 8,
,  ,  ,  , 6, 4,  ,  , 6,  ,  ,  ,  ,  , 8,  ,  ,  ,  , 4,  , 5,  ,  ,  ,  , 2
,  ,  ,  ,  ,  ,  ,  ,  ,  ,  , 5,  ,  , 2, 6,  , 8,  ,  , 7,  ,  , 3,  , 4,
,  ,  , 1,  ,  ,  ,  , 4,  , 8,  , 1,  ,  ,  , 9, 5, 8,  ,  ,  ,  ,  , 4,  ,
3,  , 5,  , 8,  ,  , 1, 2, 2,  ,  ,  ,  ,  , 1,  , 3,  ,  , 9,  , 6,  ,  , 8,
,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  , 4,  ,  , 5,  ,  ,  , 3, 2
9, 1, 6,  , 6,  ,  ,  ,  ,  , 7,  , 8, 9,  ,  ,  ,  ,  ,  , 9,  , 3,  ,  ,  , 9
4,  ,  ,  , 9,  ,  , 7,  ,  ,  ,  ,  , 6,  , 5, 2,  ,  , 5,  ,  ,  ,  ,  ,  ,
,  ,  ,  , 2,  ,  , 9,  , 4,  ,  ,  , 1,  ,  ,  ,  , 7,  ,  , 9,  ,  ,  , 1,
,  ,  , 6,  , 9, 6,  ,  ,  ,  ,  ,  , 7,  ,  ,  ,  ,  , 3, 1,  ,  , 7, 5,  ,
,  ,  ,  ,  ,  ,  , 9, 4, 4, 1,  ,  ,  ,  , 9,  ,  ,  , 2,  ,  , 6,  ,  ,  ,
,  , 3,  ,  , 1,  , 5, 8,  ,  , 3,  ,  , 8,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ,
,  , 2,  ,  , 7,  ,  ,  ,  ,  ,  ,  ,  ,  , 4,  ,  , 2, 4,  , 4,  ,  , 9, 4,
, 8,  ,  ,  ,  ,  ,  , 2,  ,  ,  , 3,  ,  ,  ,  ,  , 3, 7,  ,  ,  , 3,  ,  ,
,  , 6,  ,  ,  ,  , 8, 7, 5,  ,  , 8,  , 7,  , 1,  ,  ,  ,  , 6,  , 8,  ,  , 7
, 1,  ,  ,  ,  ,  , 2,  ,  ,  , 2,  , 3,  , 5, 2,  , 8, 6,  , 3, 2,  ,  ,  ,
, 7, 5,  ,  ,  ,  , 6, 1, 5, 7,  ,  , 8,  ,  ,  ,  , 1,  ,  , 5,  ,  ,  ,  ,
,  , 6,  , 7,  , 3,  , 8,  , 4, 9,  ,  , 6,  ,  ,  ,  , 9, 4,  , 4,  ,  ,  ,
• instructions? are we supposed to know how this is different from a regular sudoku? Sep 3, 2020 at 1:02
• I would have thought you’d have 3 copies of each number in every row / column, but there are four 2s in the last column and other places, so, what’s going on here? Sep 3, 2020 at 1:09
• Each of the 9x9 squares can't be a standard sudoku tho, cuz look at the top right one, there are two 2s in the right-most column Sep 3, 2020 at 2:57
• @ShubhamGoenka Nope, that's part of the puzzle :)
– Avi
Sep 3, 2020 at 3:54
• Maybe completely off-base, but - using 'least favourite moderator' as a clue, the mod for Puzzling with the lowest reputation score (from puzzling.stackexchange.com/users?tab=moderators) has a Rubik's Cube on the shirt of his avatar. Maybe there's something rotation-related involved here? Sep 3, 2020 at 6:55

As others have seen, the 9 sudokus are generally unsolvable because they have numbers which repeat in rows and/or columns. However, there is one exception, which is the central sudoku. It turns out it is solvable and with a unique solution:

There is something striking about the solution, namely that the central 3x3 square has a very nice ordering of its numbers. Suppose the central sudoku is a mapping of the total sudoku such that each 3x3 square in the central sudoku shows how each 9x9 sudoku has had its 3x3 squares moved around. For example, in the top left 3x3 square of the central sudoku, the number 1 is in the middle of the left column. Suppose this means that the top left 9x9 sudoku has had its "number 1" 3x3 square moved to the middle of its left column, when it should in fact have been at the top left (in the order given by the central suduko's central square). If we rearrange the position of each 3x3 square of each 9x9 suduko so it matches the ordering of the central sudoku's central square, we get this:

And if we then check each 9x9 sudoku, we see that there are no longer any repeats of numbers in rows or columns. In fact, each of the sudokus are now solvable and with unique solutions:

• This is a really nice spot! But I think your middle picture might be in error as things stand - it seems to be the same as the first without the central 9x9 (nothing has changed position...)?
– Stiv
Sep 3, 2020 at 22:40
• @Stiv Arghh, you are right. Will fix...
– Jens
Sep 3, 2020 at 22:42
• @Stiv Should be fixed now. Thanks for the heads up!
– Jens
Sep 3, 2020 at 22:56
• The moderator, freed from the Sudoku, peers at you suspiciously. They shake their head, and vanish into moderator-land
– Avi
Sep 4, 2020 at 0:32