Practise: Naked Quad
This verified teaching position begins directly with a real Naked Quad pattern. Follow the chain, inspect the candidates and make the deduction before you continue.
You are at the verified key position. Use a hint to follow the chain link by link when you need support.
How to spot it
Quads are easiest to find in units where only five or six cells remain empty, because then the quad is nearly the whole unit. Look for four cells whose candidates are drawn from a small pool of digits, and check whether the union is exactly four.
Put it to use
Where you will meet it
Hard grids are built around moves like this one. That is where it earns its keep.
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Type the position into the solver and it walks the whole solution, naming the technique behind every step — including this one.
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