A Naked Triple is three cells that contain a combination of the same three candidates and are part of the same group. Any other cells in the same group cannot contain the three candidates as those candidates can only be in the Naked Triple cells.
If one of the Naked Triple cells takes a given value, then the other cells in the Naked Triple MUST take the other two values. And if the second triple cell takes on a second value, the last cell must take on the final value. Therefore no other cells can have these three candidates in the group containing the Naked Triple.
All 3 candidate do not have to appear in all 3 cells, but they must not form a naked pair. If A, B and C are the candidate values, the following combination of values in the cells are possible:
[(ABC),(ABC),(ABC)], [(ABC),(ABC),(AB)], [(ABC),(ABC),(AC)], [(ABC),(ABC),(BC)], [(ABC),(AB),(BC)], [(ABC),(AC),(AB)], [(ABC),(AC),(BC)], [(AB),(AC),(BC)]
5, 8 and 9 form the naked triple in Box 5.
That means that candidates 5, 8 and 9 can be removed from cells [4,4], [4,6] and [6,4] .
4, 5 and 7 form the naked triple in Row 3.
That means that candidates 4, 5 and 7 can be removed from cells [3,3],[3,4],[3,5] and [3,6].
5, 7 and 9 form the naked triple in Column 4.
That means that candidates 5, 7 and 9 can be removed from cells [3,4],[4,4] and [8,4].
If you tap on the following links on an iOS device which has the Sudoku Tutor app installed, it will launch the app and open the practice puzzle. Tap hint once the puzzle is open to see the strategy in action.
Sample Puzzle 1 Sample Puzzle 2 Sample Puzzle 3Back to Sudoku Solvers or continue to next algorithm Hidden Triple