Hidden Triple Sudoku Technique
The Hidden Triple is a powerful intermediate Sudoku solving technique that can help you make progress on tougher puzzles when basic strategies are no longer enough. By learning to spot hidden triples, you can eliminate candidates and unlock cells that might otherwise seem impossible to solve.
What is a Hidden Triple?
A hidden triple occurs when three numbers are candidates in exactly three cells within a single row, column, or 3x3 box—but those cells may also contain other candidates. The key is that those three numbers must not appear as candidates anywhere else in that unit. Once you identify a hidden triple, you know that those three numbers must occupy those three cells in some order, allowing you to eliminate all other candidates from those cells.
Example:
Suppose in a row, the numbers 2, 5, and 7 are only candidates in three cells, but those cells also have other candidates (like 1, 3, or 9). You can safely remove all other candidates from those three cells, leaving only 2, 5, and 7.
How to Spot a Hidden Triple
- Scan a row, column, or box for three numbers that are candidates in exactly three cells within that unit.
- Check that those three cells may have other candidates, but the three numbers do not appear as candidates elsewhere in the unit.
- Eliminate all other candidates from those three cells, leaving only the hidden triple.
Hidden Triple vs. Naked Triple
- Naked Triple: Three cells in a unit contain only the same three candidates (and no others).
- Hidden Triple: Three candidates are restricted to three cells in a unit, but those cells may have additional candidates.
Example of a Hidden Triple
Imagine you are solving a Sudoku puzzle and notice that in a particular row, the numbers 3, 6, and 9 are only possible in cells A, D, and F. Even if those cells also have other candidates (like 1 or 7), you know that 3, 6, and 9 must occupy those three cells. You can now remove any other candidates from cells A, D, and F.
Why Use the Hidden Triple Technique?
The hidden triple technique is especially useful in medium and hard Sudoku puzzles, where simple elimination and singles are not enough. By mastering this strategy, you can break through tough spots and solve puzzles more efficiently.
Practice the Hidden Triple
Ready to put this technique to the test? Try spotting hidden triples in your next Sudoku game, or play a puzzle now and see how much faster you can solve with this powerful strategy.
Want to learn more? Explore our other Sudoku techniques or check out our strategy articles for more tips and tricks!