TECHNIQUE · INTERMEDIATE
Pointing Pair — a box points along a line
When all candidate cells for a digit inside a box lie on the same row or column, that digit must land on that line within the box. Every other cell on the line outside the box can be cleared of the digit.
The logic
The digit must appear once in the box. If its candidates inside the box share a single row or column, the box's placement will fall on that line. The same line in other boxes therefore cannot carry the digit.
How to find it
Examine each box's unplaced digits. If the candidate cells (two or three) all sit on one row or one column, you have a Pointing Pair (or triple).
- Pick a box with many remaining candidates.
- List candidate cells for each unplaced digit inside the box.
- Check whether all candidate cells lie on a single row or column.
- Eliminate the digit from that row or column outside the box.
Pair with Box/Line Reduction
Pointing Pairs go box → line. Box/Line Reduction goes line → box. Together they make up Locked Candidates and clear large swaths of Hard and Expert candidate noise.
Practice order
- Pick a boxChoose a box with many remaining candidates.
- Map candidatesRecord candidate cells per unplaced digit inside the box.
- Check alignmentVerify all candidates of one digit sit on one row or column.
- Clear the lineRemove the digit from that row/column outside the box.
Walk through a Pointing Pair
Step 1 of 4
Look at the top-left box (rows 1–3, columns 1–3). Rows 2 and 3 are already filled with 1, 2, 3 and 4, 6, 7. The only empty box cells are in row 1.