The answer: 6, 670, 903, 752, 021, 072, 936, 960, according to this site:
I have tried to get this number using direct methods but basically I have found the question too hard. There are too many possibilities, but I am likely missing some strategic ways to solve the problem. Any help would be greatly appreciated, thanks.
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$\endgroup$ 2 $\begingroup$Try Wikipedia for an introduction and overview and additional references.
$\endgroup$ $\begingroup$I think it would be (9!)squared X 9 The 9 is from the 9 different puzzles with the center number changed. Then you would have to subtract all the puzzles with 0 thru 7 solved numbers(if you had the 8th solved, the empty spaces would be the next solved number and the puzzle)
$\endgroup$ $\begingroup$Based on the equation (9!^2(9)), the number of possible sudoku puzzles is exactly 1,185,137,049,600.
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