su¦do¦ku in Excel
A su¦do¦ku puzzle is a 9×9 grid made up of 3×3 sub grids (called "regions"), where at the beginning some cells already contain numbers, known as "givens". The goal is to fill in the empty cells, one number in each, so that each column, row, and region contains the numbers 1 through 9 exactly once. Each number in the solution therefore occurs only once in each of three "directions". Full instructions for solving the grids are in the model.
You can enter your own puzzles or load puzzles on to the grid. Try to solve the missing cells and press 'Check Solutions' when you have finished. The model will stop you entering incorrect values. Alternatively press 'Check Puzzle' to load the check screen where all the possibilities are marked for you.
The possibilities for each cell are marked and you can now try to solve those cells with the least possible entries. In the example below a number of cells have only one possibility on this easy puzzle.
You can press 'Auto Solve Puzzle' at any time and the model will loop and try to enter the correct digit for each cell. The image below shows a completed solution.