sudokUI › Sudoku techniques › Naked Pair
Naked Pair in sudoku
flip side of a hidden subset · in a line: X-Wing sideways · how it fits
Two cells in the same unit that each hold exactly the same two candidates, X and Y, and nothing else.
Why it works
One cell must take X and the other Y, in either order, so neither digit can go anywhere else in a unit that contains both cells. Remove X and Y from all other cells of each such unit.
How to spot it
Find two bivalue cells that see each other and show the same two digits, then look for those digits elsewhere in every unit they share.
Worked example
Naked Pair: cells r9c2, r9c7 contain only 2/5, removing those digits from the cells they all see. So 5 is removed from r9c6.
Practise it on a real puzzle. sudokUI generates a puzzle that needs Naked Pair and takes you straight to the position where it applies. Hints draw the pattern on the board and explain the step.
In a puzzle's rating
Each time the solver needs Naked Pair, the puzzle's difficulty rating grows by 60. Its class is Medium. It is needed in 14% of puzzles that sudokUI generates. How the rating works.
More subsets
Naked Triple · Hidden Pair · Hidden Triple · Naked Quadruple · Hidden Quadruple