Sudoku
How to Solve Sudoku Step by Step
A practical approach to Sudoku using scanning, candidate notes, and logical deductions.
Start with cells you can solve
Scan each row, column, and 3×3 box. If only one digit can fit in a cell, place it and update the surrounding cells.
Then look for a digit that has only one possible position within a row, column, or box. This hidden single can reveal more straightforward placements.
Use candidate notes with purpose
For an unsolved cell, write down the digits that do not already appear in its row, column, or box. Remove candidates as new placements rule them out.
Avoid guessing while a logical move is available. Each placement should follow a rule that you can check afterward.
Follow a repeatable solving routine
Find singles, update candidates, and look for naked pairs. If two cells in the same unit contain the same two candidates, those digits can be removed from the other cells in that unit.
Repeat the scan after every placement. When progress stops, move to a more advanced technique instead of filling a cell at random.