You can add symbols too, such as question marks. If you prefer to enter your own pencilmarks, up to six digits can be entered in each cell. These update by themselves as you solve particular cells and cannot be edited manually. There are automatic pencilmarks that appear if you check the Pencilmarks box. So it's possible to have incorrect digits that don't conflict, but eventually you will get stuck.

The Show Conflicts button does not apply the solving logic - just checks whether there are any conflicting digits already in the grid. To print the puzzles use either the Print button below the grid, or if you want to print the pencilmarks as well, use the browser Print option under the File menu. See our guide to solution rules for hard sudoku puzzles.Īll the puzzles on this site rate a 'fiendish' category, but then we picked the hardest, and graded them in five progressively more difficult categories: Evil, Excessive, Egregious, Excruciating, and Extreme, in order from least difficult to most difficult. Difficulty depends on the type of steps required to solve them, and also on the number of each type of step. Solving these puzzles is a different matter entirely, since these are the most difficult puzzles we create. Each row, column, and 3 x 3 box must contain only one of each of the 9 digits. Just place the digits from 1 to 9 in each empty cell. Then try some of our very hard sudoku puzzles.

Sudoku+ HD free instals