Ready to put Box/Line Reduction into action? This page is designed for you to practice and master Box/Line Reduction with positions from real Sudoku puzzles.
Every board above is a position from a real puzzle where the Box/Line Reduction is the next step. Tap the candidates it removes (or select a cell and press the digit) and press Check. If you’re stuck, Show me gives the answer and Next puzzle loads another. Want to watch one first? Switch to Worked example.
What is Box/Line Reduction?
Box/Line Reduction (also called claiming) is the mirror image of a pointing pair. When every place for a candidate in a row or column lies inside one 3x3 box, that box’s copy of the candidate must be on that line. So you can remove the candidate from the other cells of the box.
Want a full step-by-step guide? Read the Box/Line Reduction technique article
How to Practice
- Pick a row or column and, for each candidate, check whether all of its places sit inside a single box.
- If they do, that candidate can go from every other cell of that box.
- On the board, tap each of those candidates to remove it.
- Press Check. On your first try you see how many you found; on the second, the ones you missed get a dashed ring.
Start Practicing on Full Puzzles
Once you can find the Box/Line Reduction on most boards without pressing Show me, take it into a full game. Medium puzzles are where this technique starts to come up, and the step-by-step solver will name the technique each time you get stuck.