Pointing Pairs Technique in Sudoku
When candidate notes in a 3×3 box align along a single straight line, they "point" out into the row or column, locking that number and eliminating it from the rest of the line.
Interactive Pointing Pair Trainer (Row 1)
In Box 1 (top-left), candidate digit 4 only appears in Row 1 (R1C1 and R1C2). Click Solve to eliminate 4 from R1C4 and R1C8.
How to Identify a Pointing Pair
Scan Box Candidates
Look at each 3×3 box and identify any digit that appears only 2 or 3 times as a pencil mark.
Check Collinear Alignment
Verify whether all instances of that candidate inside the box share the exact same row or column.
Prune the Outer Line
Follow the line outside the box and safely remove that candidate from all other cells in the line.
Frequently Asked Questions
What is a Pointing Pair in Sudoku?
A Pointing Pair (also known as Locked Candidates Type 1) occurs when a candidate digit inside a 3×3 box is restricted to only two cells, and both of those cells lie along the exact same row or column. Since the digit must be placed in one of those two cells to satisfy the box, it cannot appear anywhere else along that entire row or column.
What is the difference between Pointing Pairs and Pointing Triples?
The logic is identical. A Pointing Pair involves 2 cells in a box aligned in a row or column, while a Pointing Triple involves 3 cells in a box aligned in the same row or column. Both lock the candidate into that line, eliminating it from the rest of the line outside the box.
Why is Pointing Pairs considered a fundamental technique?
Pointing Pairs is often the first candidate elimination technique required when transitioning from Medium to Hard Sudoku puzzles. It eliminates pencil mark clutter and frequently reveals Naked Singles or Naked Pairs.
Next Up: Box-Line Reduction
Learn the reverse technique where a row or column restricts candidates into a single box.