The four Sudoku techniques that take you from guessing to solving: scanning, pencil marks, naked pairs and pointing pairs.
Every Sudoku on PlayJoy has exactly one solution and can be finished without guessing. That is a guarantee, not a hope — our generator throws away any board whose answer is not unique. So if you are stuck, it is a technique gap, not an impossible board.
Technique 1 — Crosshatch scanning
Pick a digit, say 7. Look at the three boxes that together cover one row. In two of them, a 7 already exists, which eliminates two-thirds of the row. Whatever cells remain in the third box's row segment are your candidates. Repeat for all nine digits before touching pencil marks.
Technique 2 — Pencil marks, used sparingly
Write candidates only in cells with two or three possibilities. A cell with five candidates tells you nothing and clutters the board. Most medium boards fall to scanning plus a handful of two-candidate cells.
Technique 3 — Naked pairs
If two cells in the same row, column or box contain exactly the same two candidates, those two digits are locked to those cells and can be removed from every other cell in that unit. It sounds trivial; it unlocks most medium boards.
Technique 4 — Pointing pairs
Within a box, if a candidate digit can only sit in cells that share a row, that digit must be in that row inside the box — so it cannot appear anywhere else in that row outside the box. This is the first technique that feels genuinely clever, and it is the one that breaks hard boards open.
FAQ
Do I need to guess on hard boards?
No. Every PlayJoy Sudoku is verified to have a unique solution reachable by deduction.
How do I get faster?
Scan before you mark. Most beginners slow themselves down by writing candidates everywhere before scanning once.