## Ken's Puzzle of the WeekSudoku Through a Cube

 Place one digit (1-9) into each unit cube of a 3x3x3 cube such that each square layer of nine unit cubes contains all nine digits.  There are nine such square layers, three in each of the three directions.
Source: Original.
Solutions were received from Tony Wang, Mark Rickert, Claudio Baiocchi, Kirk Bresniker, Joseph DeVincentis, Alan O'Donnell.  Most discovered you could simply shift the top-layer for use in the middle and bottom layers.  An example of such is from Joseph:

123 978 564
456 312 897
789 645 231

Tony's solution stood out because it did NOT use a shifted version of the top layer for lower layers:

1 2 3
4 5 6
7 8 9

9 6 4
8 1 7
2 3 5

5 7 8
3 9 2
6 4 1

Kirk suggests a complete set of 40 solutions, after removing rotations and reflections is:

```123456789 564897231 978312645
123456789 564897312 978231645
123456789 564978231 897312645
123456789 564978312 897231645
123456789 567891234 948372615
123456789 568397241 974812635
123456789 574892631 968317245
123456789 578392641 964817235
123456789 594837261 678912345
123456789 597831264 648972315
123456789 645897231 978312564
123456789 645897312 978231564
123456789 645978231 897312564
123456789 645978312 897231564
123456789 647938512 895271364
123456789 648972315 597831264
123456789 675918342 894237561
123456789 678912345 594837261
123456789 695278314 847931562
123456789 697238514 845971362
123456789 845971362 697238514
123456789 847931562 695278314
123456789 864297531 975318642
123456789 867291534 945378612
123456789 894237561 675918342
123456789 895271364 647938512
123456789 897231564 645978312
123456789 897231645 564978312
123456789 897312564 645978231
123456789 897312645 564978231
123456789 945378612 867291534
123456789 948372615 567891234
123456789 964817235 578392641
123456789 968317245 574892631
123456789 974812635 568397241
123456789 975318642 864297531
123456789 978231564 645897312
123456789 978231645 564897312
123456789 978312564 645897231
123456789 978312645 564897231```

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