Naked Quad Walkthrough

A Naked Quad is four cells in a unit whose candidates come from only four digits. Those digits are locked into the four cells and can be eliminated from the rest of the unit.

Sudoku board with pencil-mark candidates before applying the Naked Quad technique — Before — candidates pencilled in. There is a Naked Quad in Block 1.

There is a Naked Quad in Block 1. Applying the Naked Quad eliminates 9 candidates (struck out in red below; any solved cells shown in green).

The same Sudoku board after the Naked Quad technique eliminates 9 candidates — After applying the Naked Quad.

Learn the Naked Quad technique →Practice it on a real puzzle →