Help Read the help page on Sudoku puzzles for a more detailed explanation.
Keyboard Usage[only when your cursor is in the grid] Note: not all options work on all browsers. Ctrl + Arrows = move around the grid. a = auto-pencil marks. p = show a pinned square. Shift + # = show squares with a <#>.
Uniqueness Each puzzle has exactly one solution, which can be found using logic alone and no guesses are ever required. If you think you've found another solution, then please double check the rules.
Unique Reference = [Sudoku-20180712-Hard-268171]
This output is generated each time you click 'Export'.