Sudoku Strategy: 8 Techniques That Solve Most Puzzles
These techniques go from the first thing to try to what hard puzzles need. Start with the rules if you're new.
1. Scan one digit at a time
Pick a digit, say 7. For each box without a 7, rule out the rows and columns that already have one. Often a single cell is left.
2. The only cell in a row, column or box ("hidden single")
If a digit can go in only one cell of a row, column or box, it goes there, even if that cell could hold other digits.
3. The only digit for a cell ("naked single")
If eight different digits already appear in a cell's row, column and box, the ninth is the answer.
4. Start with the busiest digits
Digits that are already placed six or seven times are the easiest to finish.
5. Use notes
On medium and hard puzzles, pencil in every candidate for a cell. kawu removes notes automatically when you place a digit.
6. Pairs
If two cells in a unit can only hold the same two digits, those digits can't go anywhere else in that unit. Remove them from the other notes.
7. Pointing pairs
If, inside a box, a digit can only go in one row, it can't go in that row in the other boxes.
8. Stuck? Change the unit
Switch from scanning digits to checking cells, or look at columns instead of rows. A fresh angle usually turns up the next move. Hint shows the easiest cell if you need it.
Frequently asked questions
What is the first thing to do in a Sudoku?
Scan for each digit in turn, starting with the digits already placed most often, and look for boxes where it can only go in one cell.
Last updated 2026-10-18