Naked Triple in Sudoku: How to Spot It
Learn the Naked Triple Sudoku technique: three cells in one unit reserve three candidates, allowing eliminations from the rest of that unit.
Guided example
See the Naked Triple on this board
Read this as one teaching unit: first identify the active unit, then the marked pattern cells, then the candidates removed or maintained.
Quick answer
A Naked Triple in Sudoku is a set of three cells in one unit whose candidates are limited to the same three numbers. Those three numbers must fill those cells, so you can remove them from every other cell in that unit.
How to spot it
Follow the board in order
- 1 Pick one row, column, or box with several candidate notes.
- 2 Look for three unsolved cells whose notes use only the same three numbers, such as 1, 5, and 9.
- 3 Confirm no cell in the triple contains a fourth candidate.
- 4 Remove those three numbers from every other cell in that same unit.
What is a Naked Triple?
A Naked Triple appears when three cells in the same row, column, or 3×3 box can only contain the same three numbers between them.
The cells do not need to have identical notes. One cell may show 15, another 59, and another 159. Together they reserve 1, 5, and 9 for those three cells.
When to look for it
Look for Naked Triples after basic singles and pairs stop producing progress. They are most useful in rows, columns, or boxes with several candidate notes but no obvious placement.
Start scanning units where you already see a Naked Pair shape, then check whether a third related cell completes a three-number set.
Example walkthrough
This walkthrough uses a real hard app puzzle tagged Naked Triple. In row 3, the blue cells r3c3, r3c4, and r3c7 contain only the digits 1, 3, and 6 between them. Those three cells reserve those three digits, so r3c8 loses 1, 3, and 6.
Why the elimination works
A row, column, or box cannot repeat numbers. If the three triple cells contain only 1, 3, and 6, those numbers must be placed inside those cells in some order.
Any other cell in the same unit using 1, 3, or 6 would leave the triple without enough numbers, so those candidates are impossible outside the triple.
Naked Triple vs. Hidden Triple
A Naked Triple is visible because the three cells contain only the triple numbers.
A Hidden Triple is hidden because the three numbers appear only in three cells, even if those cells contain extra candidates at first.
Common mistake
Do not include a cell with a fourth candidate unless that candidate is eliminated by some other rule first. A cell showing 1, 5, 8, and 9 is not part of a Naked Triple for 1/5/9 yet.
FAQ
What is a Naked Triple in Sudoku?
A Naked Triple is three cells in one row, column, or box that together contain only three possible numbers.
How is a Naked Triple different from a Naked Pair?
A Naked Pair uses two cells and two numbers. A Naked Triple uses three cells and three numbers.
Do the three cells need identical notes?
No. The cells can show combinations like 15, 59, and 159 as long as the union is exactly three numbers.
What should I do after finding a Naked Triple?
Remove the triple's numbers from other cells in the same unit, then look for new singles or pairs.
In this lesson
- Board example: see the pattern first.
- Walkthrough: connect each highlight to the rule.
- FAQ: check edge cases after the move is clear.
Practice this technique in Sudoku Coach
Read the pattern, then practice it step by step with guided hints that explain why the move works.
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