How to Use Notes (Candidates) in Sudoku
How to jot down possible numbers in a cell, and tips for keeping your notes up to date.
What notes are
Notes are small numbers you write inside a cell to show which numbers could go there. On this site, press the Notes button and then a number to write it as a candidate.
How to write them
Notes in every cell get hard to read. At first, write them only in cells with just two or three candidates. That makes it easier to notice techniques such as pairs.
Don't forget to erase
Whenever you place a number, remove it from the notes of the cells in the same row, column and box. On this site, placing a number automatically erases the related notes.
The next step
With notes, you can start to see the next techniques, such as pairs and the relationship between boxes and rows.
More articles: Sudoku Rules and How to Get Started / The Two Basic Sudoku Techniques: Singles (One Number per Cell, One Cell per Number) / Sudoku Techniques: Pairs (Naked Pair and Hidden Pair) / Sudoku Techniques: Boxes and Lines (Pointing Pairs) / Sudoku Techniques: X-Wing / Sudoku Techniques: Trial and Error (for Demon, Hell and Abyss) / How Kids Can Play Sudoku (6×6)
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