What Is a Pointing Pair?
A pointing pair occurs when a candidate number within a 3×3 box is restricted to just one row (or one column) inside that box. Because the number must go somewhere in that row within the box, it cannot appear in that same row outside the box. So you eliminate it from those external cells.
The name "pointing" comes from the visual — the two (or three) candidate cells in the box "point" along a row or column, and everything they point at outside the box loses that candidate.
Why It Works
Think about it from the box's perspective. The box needs this number somewhere. If the only cells where it can go are in Row 4, then Row 4 within the box will definitely contain this number. That means Row 4 outside the box cannot also contain it — there is only one of each number per row.
This is a box-to-line elimination: the box constraint forces information onto the line (row or column), which then eliminates candidates elsewhere on that line.
How to Spot Pointing Pairs
Step 1: Pick a 3×3 box and a candidate number. Look at where that candidate appears within the box.
Step 2: If all instances of that candidate are in the same row, you have a pointing pair (or triple) along that row. If they are all in the same column, you have one along that column.
Step 3: Eliminate that candidate from all other cells in that row (or column) that are outside the box.
That is the complete technique. The tricky part is remembering to check each box systematically rather than hoping to stumble on one by accident.
Systematic Scanning Method
For each of the 9 boxes, check each missing number: is it confined to one row or one column within the box? If yes, eliminate from the rest of that line. With practice this becomes a quick visual scan — you are looking for candidates that line up horizontally or vertically within a box.
Worked Example
Consider Box 1 (top-left, rows 1–3, columns 1–3). The candidate 6 appears in the following cells within this box:
R1C1: {2, 6} — R1C3: {6, 9} — R2C2: {2, 9} — R3C1: {2, 9}
The candidate 6 appears only in R1C1 and R1C3 — both in Row 1. This is a pointing pair for 6 along Row 1.
Now look at Row 1 outside Box 1: cells R1C4 through R1C9. If any of those cells have 6 as a candidate, erase it. For example, if R1C7 has candidates {3, 6, 8}, it becomes {3, 8}. That elimination might create a naked single or enable another technique.
Pointing Pairs vs. Box-Line Reduction (Claiming)
These are complementary techniques that work in opposite directions:
Pointing pair (box → line): A candidate in a box is restricted to one row or column. Eliminate from the rest of that row or column.
Box-line reduction / claiming pair (line → box): A candidate in a row or column is restricted to one box. Eliminate from the rest of that box.
Both are equally valid and equally common. Experienced solvers check for both at the same time: whenever you examine a box, check if candidates point outward (pointing pair); whenever you examine a row or column, check if candidates are confined to one box (claiming pair).
Common Mistakes
Eliminating inside the box. The pointing cells are in the box. You eliminate outside the box, in the rest of the row or column. Never remove candidates from the pointing cells themselves.
Missing the column version. Pointing pairs work along rows and columns equally. If the candidate is confined to one column in the box, eliminate from that column outside the box. Do not only check rows.
Incomplete candidate lists. If your pencil marks are not up to date, you might think a candidate is restricted to two cells when it actually appears in a third. Always update marks before scanning for intermediate techniques.
Confusing with naked pairs. Naked pairs involve two cells with the same two candidates. Pointing pairs involve cells that share a number and a line within a box. They are different patterns that do different things.
Not checking all 9 boxes. A pointing pair can appear in any box. Scan all nine systematically rather than checking only the area you are currently working on.
Forgetting to chain. After a pointing pair elimination, re-scan. The elimination might have created a hidden single or reduced a cell to a naked single. Always follow up.
Practice
Pointing pairs appear frequently in medium and hard puzzles. They are rare in easy puzzles (which usually solve with singles alone) and are a crucial stepping stone between basic scanning and advanced techniques like X-Wing.
Try the Deluxe Player on Hard difficulty with the mistake toggle on. Fill in pencil marks for a region, then deliberately scan each box for pointing patterns. With the mistake toggle, you can verify your eliminations are correct.
For paper practice, print a hard pack and highlight (circle or underline) every pointing pair you find before making the elimination. This trains your eye to recognize the pattern at a glance.
Frequently Asked Questions
What is the difference between a pointing pair and a claiming pair?
A pointing pair eliminates from a row or column based on box constraints. A claiming pair eliminates from a box based on row or column constraints. They work in opposite directions but follow the same logic.
Do I need pencil marks?
Yes, almost always. Pointing pairs require knowing which candidates are possible in each cell. Cross-hatching might occasionally reveal the pattern, but pencil marks make it reliable.
How common are pointing pairs?
Very common in medium and hard puzzles. They often appear multiple times in a single puzzle and are one of the first intermediate techniques solvers learn after singles.
Can it involve three cells instead of two?
Yes. When a candidate in a box is restricted to three cells in the same row or column, it is called a pointing triple. The elimination logic is identical.