What is a pointing pair?
A pointing pair happens when a number can go in only two cells of a 3 × 3 box, and both cells are in the same row or column. The box must hold the number in one of them, so that line’s copy of the number is inside the box. You can remove the number from the rest of the line outside the box.
With three aligned cells it is called a pointing triple. Both are part of a family called locked candidates. In Marble Sudoku you look at where one marble color can still go.
Use one in 3 moves
- 1Box. Pick a box and a number it still needs.
- 2Line up. Check whether all its possible cells are in one row or column.
- 3Clear. Remove the number from that line outside the box.
Then look for singles where you removed it.
TRY IT · GUIDED EXAMPLE
Let the box point
Only Navy is shown in color. Faded Navy marbles mark every hole where Navy could still go. Find where Navy can go in the glowing box, follow where it points, and clear the way.
This is the real board from Marble Sudoku. The nine marble colors stand for the numbers 1 to 9.
- Find
- Clear
- Place
STEP 1
Let the box point
Read the example in words
In the bottom-left box, Navy can only go in row 9, columns 2 and 3. So the bottom-left box’s Navy is in row 9, and row 9 can’t have another Navy. That removes Navy from row 9, columns 6 and 7. Now the bottom-middle box has only one place left for Navy: row 8, column 6. That is a hidden single. With numbers turned on, Navy is 8.
YOUR TURN · PRACTICE
Find the pointing patterns
Each round shows the spots for one color. Tap all of that color’s spots in a box when they line up in one row or column, and watch them clear the rest of the line. On Easy the box glows. On Hard you find it yourself.
Round color:
Why a pointing pair works
Every box needs each number exactly once. If the box’s only options for a 5 are two cells in row 3, then the box’s 5 is in row 3, whichever cell it ends up in. Row 3 also needs exactly one 5, and it is already provided by the box. Any other 5 in row 3 would be a second one, so it can be removed.
The reverse also works and is called box-line reduction (or claiming): if a number’s only spots in a row all fall inside one box, you can remove it from the rest of that box.
How to spot pointing pairs faster
- Use one number at a time. Pick a number and look at its possible cells box by box, like you do for hidden singles.
- Look for boxes with two or three spots. When a box has only two or three options for a number, check whether they line up.
- Follow the line. Once you find a pointing pair, follow its row or column to the other boxes. That is where the elimination happens.
- Expect a single next. Removing a candidate along a line often leaves a hidden single in a neighboring box.
Pointing pair vs. naked pair
| Pointing pair | Naked pair | |
|---|---|---|
| Focus | One number across one box | Two cells and their candidates |
| Pattern | The number’s box spots share a row or column | Two cells share the same two candidates |
| Removes | That number from the rest of the line | Both numbers from the rest of the group |
| Needs notes? | Helpful, but you can scan it | Yes, usually |
Common mistakes
- Missing a spot in the box. Every possible cell for the number in the box must be on the line. One stray spot breaks the pattern.
- Removing inside the box. Only remove the number from the line outside the box. The aligned cells keep it.
- Using the wrong line. If the spots share a row, clear the row. If they share a column, clear the column.
- Stopping after the removal. The removal is the setup. Look for the single it creates.
Pointing pairs FAQ
What is a pointing pair in Sudoku?
A pointing pair is when a number’s only possible cells inside a 3 × 3 box are two cells in the same row or column. The number must be in one of them, so it can be removed from the rest of that row or column outside the box.
What is a pointing triple?
The same pattern with three aligned cells: all three possible spots for a number in a box sit in one row or column.
Are pointing pairs the same as locked candidates?
Yes. Pointing pairs are the first type of locked candidates. The second type, box-line reduction (claiming), works the other way: a number confined to one box within a row or column is removed from the rest of that box.
What is the difference between a pointing pair and a naked pair?
A pointing pair is about one number and where it can go inside a box. A naked pair is about two cells that share the same two candidates. Both remove candidates, from different places.
Do I need pencil marks for pointing pairs?
They help, but you can also scan: look at one number in one box and check whether its free cells line up.
Does this work in Marble Sudoku?
Yes. Pick one marble color and look at where it can go inside a box. If those holes line up, remove that color from the rest of the line.
PRACTICE IN THE GAME
Use pointing pairs in a real puzzle
When a tough puzzle stalls, look inside each box for a color that sits on one line. It is often the move that opens everything up.
Next techniqueHidden pairs
