Expert Sudoku, Play Free Online, 58 Empty Cells

How many cells are empty? 58 of 81, more than any other level. What techniques do I need? No single technique solves an expert grid on its own. You'll usually need to mark every candidate in every empty cell first, then look for chains, for example if the digit 9 can only sit in cell A alongside the digit 2, and the digit 2 in cell B can only sit alongside 9, those two cells form a rigid link, and that often lets you eliminate a digit in a third, seemingly unrelated cell (this is the X-Wing technique). How long does it take? Anywhere from 30 minutes to an hour per grid. What if I get stuck? That's completely normal, go back to hard sudoku to lock in the intermediate techniques and come back later. Like every level here, it's free and requires no sign-up.