A hidden pair occurs when two digits can only be placed in the same two cells within a house.
Understanding the Concept
Two candidates appear in only two cells within a house (row, column, or box).
These two cells might have other candidates, making the pair "hidden".
Since these two digits must go in these two cells, all other candidates can be removed from these cells.
After cleanup, it becomes a naked pair.
Example: If digits 3 and 7 only appear in cells A and B within a row, then A and B can only contain 3 or 7.
Hidden pairs are harder to spot than naked pairs but equally powerful.
Examples
Hidden Pair Example
In a column, if digits 5 and 8 only appear in cells R2C4 and R7C4 (which might have other candidates too), then all other candidates can be removed from these two cells.
Pro Tips
- •For each pair of digits, check where they can go in each house
- •If both are limited to the same two cells, you have a hidden pair
- •After finding one, clean up the cells to show only the pair
- •Hidden pairs often become naked pairs after cleanup
