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Sudoku Solver

Tool/Solver to resolve sudoku/wordoku grids (directly or step by step). Sudoku is a game whose purpose is to fill a 9x9 grid with digits (or letters/symbols) in order to get only one per line, column and block (a delimited portion of the grid), by defaut sub-grid 3x3.

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Sudoku Solver -

Tag(s) : Number Game

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# Sudoku Solver

## Solve a sudoku grid

 Resolution Compute all solutions Step by Step Solution

Tool/Solver to resolve sudoku/wordoku grids (directly or step by step). Sudoku is a game whose purpose is to fill a 9x9 grid with digits (or letters/symbols) in order to get only one per line, column and block (a delimited portion of the grid), by defaut sub-grid 3x3.

### How to fill the Sudoku grid?

Make a copy/paste or type directly in cells. Letters (Wordoku) and digits are accepted.

Example: Copy the Sudoku content in the first cell (top left) 97 1 5 5 9 2 18 4 8 7 26 92 3 6 2 9 19 457  to get :

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

### How does the step by step works?

Software solves the Sudoku like an human and display each step of its progress to understand.

Sometimes the reasoning stops at a step where no logical deduction can deduce at 100% the value of a box (several possible values). The solver performs a random pick among these possible values and continues, if an inconsistency occurs (the sudoku turns to have no solution) then it goes back to the step of the random pick and choose another value. To maximize the chances, choose a number which, if it is positioned in the cell, will allow the maximum of deduction in the continuation of the sudoku.

If the program indicates that there is only one possible value, it means that no other value is acceptable in the box.

### How to test if a sudoku has a unique solution?

dCode calculates all the solutions for the sudoku, not only the first one. To check a homemade sudoku, the solver can confirm that there is only one solution.

### When Sudoku have been invented?

The first Sudoku versions are from 1979

### How many distinct sudokus exist?

A line can consist of $$9!$$ (Factorial of 9) different ways, but the whole sudoku has a number of possibilities much less than $$9!^9$$, because some permutations can lead to identical grids. The total number of grids would be $$9! \times 72^2 \times 27 \times 27 \times 704267971 = 6670903752021072936960$$ combinations.