David's Sudoku Solver

You will find a lot of Sudokus in newspapers, magazines and books. Sometimes you need help to solve the Sudoku or have not got something to write with you. In such cases, the app is handy for your smartphone ot tablet. If you wish, the app can show used numbers and hide or show possible candidates for a cell. When you want, you can also ask for a tip including the reason why. Of course you can also save a Sudoku and retrieve it for later solving. The numbers appear in different colours: blue for original numbers, black for your solution numbers and red for mistakes (where the number has already been entered in the row or column). A solvable Sudoku should have only one solution. The app can check and tell you the number of solutions. An X-Sudoku is a Sudoku where the main diagonals also include the numbers 1 to 9 only once. A hint for people who enjoy competitions. When all participants enter the same Sudoku in their devices, then they can have fun seeing who finishes first.