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## 'A First Product Sudoku' printed from http://nrich.maths.org/

Like the standard Sudoku, this Sudoku consists of a grid of nine
rows and nine columns subdivided into nine 3x3 subgrids.

Like the standard Sudoku, it has two basic rules:

1. Each column, each row and each box (3x3 subgrid) must have the
numbers 1 to 9

2. No column, row or box can have two squares with the same
number.

The puzzle can be solved with the help of clue-numbers which are
small numbers written on the intersections between two cells. Each
clue-number is the product of the two digits in the two cells that
are on either side of it.

For example, 8 in the top right box means that possible pairs of
numbers for cell (1,9) and cell (2,9) are either1 and 8, 8 and 1; 4
and 2, or 2 and 4 respectively.

A word document containing the Sudoku problem can be found

here.