Very Hard Sudoku Puzzles Printable
Very hard infinite sudoku puzzles totally free and printable in order to play during a travel or sit down in our living room with different difficulty levels. The rules are quite simple actually. The objective is to fill the 9x9 sudoku grid with digits 1 to 9 such that each of these 9 digits appears in each row each column and each 3x3 sub grid once any only once.