This Sudoku game is the hardest Sudoku ever! Instead of simply inserting numbers, you have to solve math equations and insert the equations into the grid.
Fun With Sudoku
Sudoku Solving Techniques – Video Tutorials.
For Beginners, Intermediate Users And The Sudoku Addict. It Covers It All. Hundreds Of Puzzles Plus Techniques To Help You Crack Them All – In Video Format.