Ready to put the Hidden Quad into action? This page is designed for you to practice and master Hidden Quad with positions from real Sudoku puzzles.
Every board above is a position from a real puzzle where the Hidden Quad 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 Hidden Quad?
A hidden quad is four digits that, within one row, column or box, can only go in the same four cells. Those cells must hold those four digits, so every other candidate in them can be removed. Hidden quads are rare and often sit opposite a naked subset in the same house.
Want a full step-by-step guide? Read the Hidden Quad technique article
How to Practice
- In a house, list where each missing digit can go and look for four digits confined to the same four cells.
- Remove every other candidate from those four cells.
- 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 Hidden Quad on most boards without pressing Show me, take it into a full game. Hard puzzles are where this technique starts to come up, and the step-by-step solver will name the technique each time you get stuck.