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📋 Hidden Pairs – Sudoku Technique

If two digits in a unit appear only in two cells, they form a hidden pair: remove all other candidates from those two cells.

What Are Hidden Pairs?

A hidden pair occurs when two digits in a row/column/box appear only in two cells of that unit (those cells may still show other candidates). Therefore, in those two cells you can remove every candidate except those two digits.

Step-by-Step Example

Step 1: In the top-left box/column, two digits occur only in two cells
1) Candidate scan reveals two digits (e.g., 1 and 2) confined to two cells.
Step 2: Confirm both digits are confined to the same two cells
2) Confirmation ⇒ a hidden pair.
Step 3: Clear other candidates inside those two cells
3) Remove all other candidates in those two cells; later direct placements may follow.

Where It Works

  • Any row,
  • Any column,
  • Any 3×3 box.

Note: Hidden vs Naked

For hidden pairs, you clear candidates inside the two cells. For naked pairs, you clear those digits from the rest of the unit.

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