Sudoku FlowSudoku technique lessons / Box/Line Reduction
Lesson 7
Box/Line Reduction
The rule
If a number on a line only fits inside one box, that candidate is removed from the rest of that box outside the line.
Step by step
- In this row, every cell where 7 can still go lies inside the same box.
- So we can remove the candidate 7 wherever it appears in that box outside that row.
Try it on more boards
Each board is a real puzzle from our app, at a moment where Box/Line Reduction applies. Find the step yourself, or tap Hint and the app's own hint walks you through it.
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