Ready to put the Unique Rectangle into action? This page is designed for you to practice and master Unique Rectangle with positions from real Sudoku puzzles.
Every board above is a position from a real puzzle where the Unique 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 a Unique Rectangle?
Four cells in two rows, two columns and two boxes that could all hold the same two digits form a deadly pattern: the two digits could swap, giving two solutions. A proper puzzle has one solution, so at least one of the cells must hold something else, and that lets you remove candidates.
Want a full step-by-step guide? Read the Unique Rectangle technique article
How to Practice
- Look for four cells at the corners of a rectangle, spanning exactly two boxes, that share the same two candidates.
- Work out which candidates must go to avoid the deadly pattern (in Type 1, the pair leaves the one cell with extras).
- 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 Unique 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.