If you’ve been solving Sudoku puzzles for a while, you’ve probably experienced the moment when every obvious move disappears. You’ve filled in all the Naked Singles, found every Hidden Single, and carefully updated your pencil marks—but the puzzle still refuses to budge.
This is where intermediate Sudoku strategies become essential.
One of the first—and most valuable—techniques you’ll want to learn is the Pointing Pair. Also known as Locked Candidates Type 1, this strategy uses the relationship between a 3×3 box and a row or column to eliminate impossible candidates and reveal new solving opportunities.
The beauty of Pointing Pairs is that they don’t require guessing or advanced mathematics. Instead, they rely on the same logical rules that govern every Sudoku puzzle.
In this guide, you’ll learn:
- What Pointing Pairs are
- Why they work
- How to identify them quickly
- Several worked examples
- Common mistakes to avoid
- How Pointing Pairs compare to similar Sudoku techniques
- Tips for spotting them faster during gameplay
Once you understand this strategy, you’ll notice it appears regularly in medium and hard Sudoku puzzles.
What Is a Pointing Pair?
A Pointing Pair occurs when a candidate digit can appear in only two cells within a single 3×3 box, and both of those cells happen to lie in the same row or the same column.
Since every digit must appear exactly once inside that box, the digit is forced to occupy one of those two cells. Because both cells share the same row (or column), that digit cannot appear anywhere else along that line outside the box.
This allows you to eliminate candidates without placing a single number.
Why Is It Called a “Pointing” Pair?
Imagine the upper-left 3×3 box.
Suppose the digit 6 can only fit in these two cells:
- Row 2, Column 1
- Row 2, Column 3
Both possible locations lie on Row 2.
Because the 6 must eventually occupy one of these cells, the box is effectively pointing toward Row 2.
That means every other candidate 6 on Row 2 outside the box is impossible.
The pair “points” to the row, giving the technique its name.
Understanding the Logic
Pointing Pairs are built on two Sudoku rules:
- Every digit appears exactly once in each 3×3 box.
- Every digit appears exactly once in every row and column.
If the only possible locations for a digit inside a box all lie on the same line, then the digit is locked to that line within the box.
Because the digit must appear there, every other occurrence of that candidate on the same row or column becomes impossible.
This interaction between boxes and lines is what makes Pointing Pairs such a powerful elimination strategy.
A Simple Example
Suppose the top-middle box has these candidates for digit 4:
- R2C4 = {4,8}
- R2C6 = {1,4}
No other cell in that box contains a candidate 4.
Notice both candidate cells are on Row 2.
Now look across the remainder of Row 2.
You find:
- R2C7 = {2,4,5}
- R2C8 = {4,9}
- R2C9 = {1,4,7}
Since the 4 must already be placed somewhere inside the top-middle box, eliminate 4 from:
- R2C7
- R2C8
- R2C9
These eliminations may immediately create a Naked Single or simplify another technique.
Pointing Pairs Can Also Work in Columns
Rows aren’t the only possibility.
Suppose the bottom-right box contains candidate 9 only in:
- R7C8
- R9C8
Both candidates share Column 8.
Because one of these cells must contain the 9, every other candidate 9 in Column 8 outside the box can safely be removed.
The logic is identical—only the direction changes.
Step-by-Step Method for Finding Pointing Pairs
Many players scan randomly across the grid, hoping a pattern will jump out.
A systematic approach is much more effective.
Step 1: Choose One Box
Focus on a single 3×3 box.
Ignore the rest of the puzzle.
Step 2: Examine One Digit
Pick a candidate digit—for example, 5.
Find every location inside the box where 5 is still possible.
Step 3: Look for Alignment
Ask yourself:
- Are all candidate 5s in the same row?
- Are all candidate 5s in the same column?
If the answer is yes, you’ve found a Pointing Pair (or possibly a Pointing Triple).
Step 4: Eliminate Candidates
Follow the shared row or column outside the box and remove that candidate from every other unsolved cell.
Step 5: Repeat
Continue checking digits 1 through 9 before moving to the next box.
With practice, this process becomes surprisingly quick.
Worked Example
Imagine the center box.
Candidate 2 appears only here:
- R5C4 = {2,6}
- R5C6 = {1,2,8}
Since both candidates are on Row 5, the digit 2 must be placed somewhere in Row 5 inside the center box.
Elsewhere in Row 5, candidate 2 appears in:
- R5C1 = {2,3}
- R5C7 = {2,4,9}
- R5C9 = {2,8}
Remove candidate 2 from each of these cells.
Suppose R5C1 becomes:
{3}
You’ve immediately solved another square without guessing.
Why Pointing Pairs Are So Effective
Many Sudoku techniques remove candidates from only one or two cells.
Pointing Pairs often affect an entire row or column.
One elimination may:
- Create a Naked Single
- Reveal a Hidden Single
- Form a Naked Pair
- Produce another Pointing Pair
- Trigger a chain reaction across the puzzle
This is why experienced solvers actively search for Pointing Pairs once basic techniques no longer produce progress.
Pointing Pairs vs. Pointing Triples
The two techniques use identical logic.
The only difference is the number of cells involved.
Pointing Pair
A candidate appears in exactly two cells inside a box.
Pointing Triple
A candidate appears in three cells inside a box, and all three lie on the same row or column.
The eliminations work exactly the same way.
Pointing Pairs vs. Box/Line Reduction
These two strategies are closely related and are often grouped under the term Locked Candidates.
However, they work in opposite directions.
Pointing Pair
- Start by examining a 3×3 box.
- The candidate is confined to one row or column.
- Eliminate candidates from the rest of that row or column.
Box/Line Reduction
- Start with a row or column.
- Notice that all candidates for a digit lie within one box.
- Eliminate the candidate from the remaining cells inside that box.
Think of them as mirror-image techniques.
Common Mistakes
Mistake 1: Forgetting the Candidate Must Be Locked
The candidate must appear only within one row or column inside the box.
If even one additional candidate appears elsewhere in the box, the Pointing Pair does not exist.
Mistake 2: Eliminating Inside the Box
Never remove candidates from the cells forming the Pointing Pair.
Those cells are the only places where the digit can go.
Only eliminate candidates outside the box along the shared line.
Mistake 3: Ignoring Pencil Marks
Pointing Pairs are almost impossible to identify without complete and accurate candidate notes.
Always update your pencil marks after every solved cell.
Mistake 4: Forgetting to Recheck the Puzzle
Every elimination changes the puzzle.
After using a Pointing Pair, scan for:
- Naked Singles
- Hidden Singles
- Naked Pairs
- Additional Locked Candidates
Many puzzles are solved through a series of these logical chain reactions.
Tips for Spotting Pointing Pairs Faster
Here are a few habits that experienced Sudoku players develop:
Scan One Box at a Time
Avoid jumping randomly around the grid.
Complete one box before moving to the next.
Focus on Digits with Few Remaining Candidates
If only three or four copies of a digit remain unsolved, Pointing Pairs become much easier to identify.
Look Immediately After Solving a Cell
Adding one digit often removes candidates from nearby boxes, creating fresh Pointing Pair opportunities.
Practice Consistently
The more puzzles you solve, the faster your brain recognizes these patterns automatically.
When Should You Use Pointing Pairs?
Pointing Pairs are most useful when:
- All obvious singles have been solved.
- Pencil marks are complete.
- Basic elimination no longer reveals new moves.
- The puzzle has reached the intermediate stage.
They are among the earliest advanced techniques that every serious Sudoku player should master and frequently appear in medium, hard, and expert puzzles.
Practice Exercise
Consider the upper-right box.
Candidate 7 appears only in:
- R1C8
- R3C8
Both candidates are in Column 8.
Elsewhere in Column 8, candidate 7 appears in:
- R4C8
- R6C8
- R8C8
Question:
Which candidates can be eliminated?
Answer:
Remove candidate 7 from:
- R4C8
- R6C8
- R8C8
Because the 7 must already appear somewhere within the upper-right box, those other candidates are impossible.
Final Thoughts
Pointing Pairs are one of the most rewarding Sudoku techniques to learn because they demonstrate how different parts of the grid work together. Instead of treating rows, columns, and boxes as separate units, this strategy teaches you to use information from one area to simplify another.
To remember the technique, keep these three rules in mind:
- Start by scanning a single 3×3 box.
- Find a candidate restricted to one row or one column within that box.
- Eliminate that candidate from the rest of the shared row or column outside the box.
Mastering Pointing Pairs will make medium puzzles feel much more approachable and prepare you for more advanced strategies like Box/Line Reduction, Hidden Pairs, X-Wings, and Swordfish.
The more you practice, the more naturally these patterns will stand out—and the fewer times you’ll ever feel tempted to guess.