Pointing Pair Sudoku Technique

Updated 11 August 2026

A pointing pair occurs when a digit can only go in two cells of a box and both of those cells lie on the same row or column, so the digit can be erased from every other cell of that line.

When a pointing pair applies

A pointing pair is the first technique on this list that never places a digit. It removes candidates, and those removals are what make the next single visible. The logic is short: every box contains each digit exactly once, so if a digit has only two possible cells left in a box and both share a row, the digit is definitely in that row. Anything else on the row, outside the box, can therefore lose the candidate.

The technique is also known as a locked candidate or box-line interaction of type one. The direction matters: a pointing pair reasons from the box outward to the line. The reverse deduction, from a line inward to a box, is box line reduction and is listed separately.

Pointing pairs are extremely common in medium puzzles. They usually appear the moment a box loses most of its blanks, because the surviving candidates for a digit get squeezed into a single band of three cells.

Worked example

The bottom-left box has four empty cells: r7c1, r7c3, r8c1 and r9c3. Only r7c1 and r8c1 can still take a 1, and they sit one above the other in column 1. Whichever of the two ends up holding the digit, column 1 gets its 1 from inside that box.

Column 1 has one other cell that still listed 1 as a candidate, r3c1, and it is now impossible. Removing it leaves r3c1 with 4, 5 and 8. Nothing was placed, but the column is one step closer to a single, which is exactly what an intersection technique is for.

How to spot a pointing pair

1. Choose a box that is missing a digitWork box by box and pick a digit the box still needs. Boxes with three or four blanks give the best odds.
2. Mark every cell in the box that can hold itCross out cells blocked by their row or column. You are looking for exactly two survivors.
3. Check whether the two survivors share a lineBoth in the same row, or both in the same column, is what makes the pair point. Two cells sitting diagonally prove nothing.
4. Erase the digit from the rest of that lineDelete the candidate from the six cells of the line that lie outside the box, then look for a naked or hidden single among them.

Common mistakes

• Erasing the candidate from the wrong direction, that is from the rest of the box instead of the rest of the line.
• Accepting two survivors that are not aligned. If the pair is diagonal inside the box, the digit is not locked to any line and there is nothing to remove.
• Forgetting that the two pair cells keep the candidate. A pointing pair says nothing about which of the two takes the digit.
• Skipping the follow-up scan. The elimination is only useful if you then look for the single it exposed.