Sudoku rules illustrated
A completed grid highlights a row, a column and a 3×3 box to show the three standard Sudoku constraints.
Hidden single Sudoku diagram
Only one cell in this row contains candidate 9, even though that cell also has candidate 4.
How to read this diagram
The row needs a 9 and only column 4 can contain it. Place 9 there and remove its other candidates.
This is a single-row teaching schematic. In a complete puzzle, row, column and box constraints all apply.
Image prepared by Sudokumax. Updated .
More to explore
All Sudoku images
X-Wing Sudoku diagram
A candidate diagram shows the four corners of an X-Wing and the sevens it eliminates in the shared columns.
Naked pair Sudoku: before and after
A row-level diagram shows two cells containing only 3 and 7, followed by the candidate eliminations they allow.