Place the numbers 1 to 9 once in each row, column, long diagonal and 3x3 box. Obviously, the central yellow-coloured 3x3 box is common to both grids.

The number in the cage (or shaded area) represents the result of an arithmetical operation by its accompanying sign. For example, 4÷ in a two-celled cage means that it contains either 8 and 2 or 4 and 1 (in any order).

Unlike Killer Sudoku, the same number may appear more than once in a cage. So, 28x in a cage which overlaps the 3x3 grids may contain two 2s and a 7.

Once again, I wish to thank brianjn most sincerely for his continued support. He converted my black and white Excel image to a coloured one in 'jpg' format.
Acknowledgement to Peter at sudexel.com for beta testing the puzzle.

I was stumped by this Sudoku -- program running forever -- until I changed the program to address a version of the puzzle that was turned 90 degrees clockwise.  It ran a whole lot faster then. 

I found five possibilities for the top grid by itself:

----------------------
9 7 3 1 5 6 4 2 8
2 1 6 9 8 4 3 5 7
8 5 4 7 3 2 1 9 6
4 6 8 2 9 3 5 7 1
1 3 9 6 7 5 8 4 2
5 2 7 4 1 8 9 6 3
3 8 2 5 4 7 6 1 9
7 9 5 8 6 1 2 3 4
6 4 1 3 2 9 7 8 5
----------------------
9 7 3 1 5 6 2 4 8
2 1 6 9 8 4 3 5 7
8 5 4 7 3 2 1 9 6
4 6 8 2 9 3 5 7 1
1 3 9 6 7 5 8 2 4
5 2 7 4 1 8 9 6 3
3 8 2 5 4 7 6 1 9
7 9 5 8 6 1 4 3 2
6 4 1 3 2 9 7 8 5
----------------------
9 7 3 1 5 6 4 2 8
2 1 6 9 8 4 3 5 7
8 5 4 7 3 2 1 9 6
4 6 8 2 9 3 5 7 1
1 2 9 6 7 5 8 4 3
5 3 7 4 1 8 9 6 2
3 8 2 5 4 7 6 1 9
7 9 5 8 6 1 2 3 4
6 4 1 3 2 9 7 8 5
----------------------
9 7 5 1 3 6 4 2 8
2 1 6 9 8 4 5 3 7
4 3 8 7 2 5 1 9 6
8 6 4 2 5 9 3 7 1
1 2 3 6 7 8 9 5 4
5 9 7 4 1 3 8 6 2
3 8 2 5 4 7 6 1 9
7 5 9 8 6 1 2 4 3
6 4 1 3 9 2 7 8 5
----------------------
9 7 3 1 5 6 4 2 8
2 1 6 9 8 4 5 3 7
4 5 8 7 3 2 1 9 6
8 3 4 2 9 5 7 6 1
1 2 9 6 7 8 3 5 4
5 6 7 4 1 3 9 8 2
3 8 2 5 4 7 6 1 9
7 9 5 8 6 1 2 4 3
6 4 1 3 2 9 8 7 5
----------------------

Only one possibility for the second grid exists, that can share that yellow
3x3 box.

So the answer I found was:

Top Grid:

9 7 3 1 5 6 4 2 8
2 1 6 9 8 4 5 3 7
4 5 8 7 3 2 1 9 6
8 3 4 2 9 5 7 6 1
1 2 9 6 7 8 3 5 4
5 6 7 4 1 3 9 8 2
3 8 2 5 4 7 6 1 9
7 9 5 8 6 1 2 4 3
6 4 1 3 2 9 8 7 5

Bottom Grid:

6 1 9 3 4 5 8 2 7
2 4 3 8 1 7 5 9 6
8 7 5 2 6 9 3 4 1
5 8 1 7 3 4 9 6 2
9 3 4 1 2 6 7 5 8
7 2 6 5 9 8 4 1 3
3 9 8 6 5 2 1 7 4
4 6 7 9 8 1 2 3 5
1 5 2 4 7 3 6 8 9
----------------------
 

 

 

 

Edited on June 23, 2008, 6:58 pm

Posted by Penny on 2008-06-23 18:57:49