Duplex Sums Sudoku, this variation of Sudoku on a
"standard" 9x9 grid contains a set of special
clue-numbers. These are small numbers always placed on
the border lines between selected pairs of neighboring
cells of the grid. Each clue-number is the product of
two numbers in the respective pair of cells of the grid
adjacent to this clue-number horizontally or vertically.
For example, clue-number 12 on a line between two
neighboring cells means that possible pairs of numbers
for these cells can be from the following combinations:
2 and 6; 3 and 4; 4 and 3; or 6 and 2.
The remaining rules are as in a "standard" Sudoku, and
the object of the puzzle is to fill in the whole 9x9
grid with numbers 1 through 9 (one number per cell) so
that each horizontal line, each vertical line, and each
of the nine 3x3 squares (outlined with the bold lines)
must contain all the nine different numbers 1 through 9.
To solve the puzzle you can print the above grid. For
this, click the image of the grid to go to a new window
with this grid; then you can print it.