Beginner

Cross-Hatching (Box)

When a number has only one possible cell left in a box.

Explanation

Pick a box and a number. Rows and columns that already contain the number cross out cells inside the box. If only one cell survives, the number goes there.

Cross-Hatching (Box) example Sudoku board 5 3 7 6 1 9 5 9 8 6 8 6 3 4 8 3 1 7 2 6 6 2 8 4 1 9 5 8 7 9
An example board where Cross-Hatching (Box) applies

Practice tip

Sweep the number across the three rows and three columns that cross the box.

Example steps

  1. Pick one box and one number to track.
  2. Cross out box cells seen by that number in its rows and columns (mark ✕).
  3. Only one cell in the box survives — place the number there.

Try this technique on a real puzzle.

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