Hidden Pair
Two values only fit in the same two cells of a row or column — strip those cells down to just those two.
How it works
- 1Ask where 1 and 2 can go in this seven-cell row: only the first two cells, for both numbers.
- 2Two numbers with only two homes between them must take one each, so neither of those cells can be holding anything else.
- 3Strike the 3 from the first cell and the 4 from the second, even though neither cell was ever down to two candidates on its own.
- 4The row has to be this long. A hidden pair among b blanks is exactly a naked set on the other b − 2 cells, and the naked rungs run first — so only seven blanks, leaving five over, put the complement out of their reach and make Hidden Pair the name a live hint actually gives.
- Candidates this technique rules out
- Cells read together — The connecting line shows which cells combine to make the deduction.
- Conclusion — The coloured candidate, or the final arrow when it lands outside the pattern, shows the result.