Pointing Pairs in Sudoku: How the Technique Works

A Pointing Pair is a Locked Candidates pattern where every remaining position for one digit inside a 3×3 box lies on the same row or column.

The box has not solved the exact cell.

It has solved something else:

The digit must appear on this particular line inside the box.

That is enough to remove the same candidate from the line outside the box.

Although Pointing Pair is the familiar name, the same logic can involve three aligned positions. VeyraPlay therefore treats Pointing Candidates as the general concept.

Quick rule

Start in a box.

If all candidate Xs in that box lie on one row:

remove X from that row outside the box.

If all candidate Xs in that box lie on one column:

remove X from that column outside the box.

Direction: box → line.

A simple example

Suppose box 5 still needs digit 7.

Candidate 7 appears only in:

r4c4
r4c6

Both cells are on row 4.

One of them must be 7 because box 5 still needs a 7.

So row 4 will get its 7 somewhere inside box 5.

Any candidate 7 on row 4 outside that box is impossible.

Notice what we did not prove:

we did not prove r4c4 = 7;
we did not prove r4c6 = 7.

We only proved:

row 4's 7 is inside this box.

That weaker statement is enough.

Step-by-step board example

Pointing can run down a column

Rotate the idea.

If all candidate 4s in a box are in column 8, then the box must place 4 somewhere in column 8.

Therefore candidate 4 can be removed from column 8 outside that box.

Pointing Pair vs Pointing Triple

Suppose a box can place digit 2 only in:

r8c4
r8c5
r8c6

All three cells lie on row 8.

The box must still place 2 somewhere on row 8, so other candidate 2s on row 8 outside the box can be removed.

Some resources call this a Pointing Triple.

It is not a different logical technique.

The important condition is:

all source candidates for the digit in the box share one line.

The number of source cells is secondary.

Why Pointing feels like advanced Crosshatching

Crosshatching already teaches you to inspect one digit inside a box.

Beginner version:

Crossing rows and columns leave one position.

→ Hidden Single.

Intermediate version:

Crossing restrictions leave several positions, but all of them share one line.

→ Pointing.

That makes Pointing a natural bridge between beginner scanning and candidate eliminations.

How to find Pointing Pairs faster

Use one digit at a time.

Step 1 — Choose a digit

Digits with several solved copies are often easier to scan because more rows and columns are already blocked.

Step 2 — Inspect boxes

In each box that still needs the digit, identify every legal candidate position.

Step 3 — Look for alignment

Do the remaining cells all share:

one row?
one column?

Step 4 — Look outside the box

If the shared line contains the same candidate elsewhere, you have a productive elimination.

Step 5 — Re-scan

The affected row/column may now contain:

a Hidden Single;
a Naked Single;
a subset.

Pointing vs Hidden Single

Both can begin with one digit inside a box.

Hidden Single

Only one cell survives.

→ Place the digit.

Pointing

Two or three cells survive, but all share one line.

→ Eliminate the digit from that line outside the box.

Think of Pointing as a partial positional solution.

You do not know the cell, but you know the line.

Pointing vs Claiming

These mirror one another.

Pointing

Start with a box.

box → row/column

Claiming / Box-Line Reduction

Start with a row or column.

row/column → box

If you mix the two up, ask:

Which unit did I inspect first to prove the restriction?

That unit is the source.

Common mistakes

Removing the digit from the source positions

The source candidates are the possible placements that make the deduction work. They remain.

Missing a third source candidate

If another legal X exists in a different row or column of the box, Pointing is not established.

Searching only for two-cell patterns

Three aligned source cells are valid too.

Eliminating from the wrong line

The elimination follows the line shared by all source candidates.

Assuming the pattern must produce a placement

The direct result is normally candidate removal.

Recognition drill

When candidate highlighting is available, practice this exact question:

“Inside this box, does digit X live on one line?”

That phrasing is fast enough to become part of your normal scan.

FAQ

Why is it called a Pointing Pair?

The two candidate positions visually point along their shared row or column toward candidates that can be removed.

Do the source cells need to be adjacent?

No. They only need to share the box and the same row or column.

Is Pointing possible without pencil marks?

Yes, especially when the grid is sparse enough to calculate positions mentally. Accurate candidates make verification much easier.

Is a Pointing Triple harder than a Pointing Pair?

It can be slightly harder to notice, but the proof is identical.

What to learn next

Learn Box-Line Reduction to reverse the direction of the same intersection logic.

Then continue to Naked Pairs, where the restriction changes from one digit in an intersection to two digits reserved for two cells.

techniques · intermediateLocked CandidatesLearn Locked Candidates in Sudoku, including Pointing and Claiming, and use box-line intersections to make logical candidate eliminations.techniques · intermediateBox-Line ReductionLearn Box-Line Reduction, also called Claiming, and use a row or column that is confined to one box to eliminate candidates inside it.techniques · intermediateNaked PairLearn how Naked Pairs reserve two digits for two cells and eliminate those candidates from other cells in the same row, column or box.techniques · beginnerCrosshatching in SudokuLearn crosshatching in Sudoku by using solved digits across rows and columns to eliminate positions and locate a digit inside a box.