Ready to put the Empty Rectangle into action? This page is designed for you to practice and master Empty Rectangle with positions from real Sudoku puzzles.
Every board above is a position from a real puzzle where the Empty Rectangle 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.
Quick Reminder: What is an Empty Rectangle?
In an Empty Rectangle, a digit’s places in one box all lie on a single row and a single column of that box (a cross). Combine that with a strong link on the digit in a line outside the box, and one cell where the two meet can lose the digit.
Want a full step-by-step guide? Read the Empty Rectangle technique article
How to Practice
- Find a box where a digit’s places all fit on one row plus one column of the box.
- Find a strong link on that digit that starts in line with the box’s row or column, then remove the digit where the other end meets the box’s other line.
- 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 Empty Rectangle on most boards without pressing Show me, take it into a full game. Evil puzzles are where this technique starts to come up, and the step-by-step solver will name the technique each time you get stuck.