sudoku.day

Naked subsets

Pairs or triples that lock digits out of a unit. medium

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The tinted cells hold only 2 digits between them, locking those digits in. Erase 2 and 4 from R5C4, R7C4, R8C4, R9C4.

If two cells in a unit hold the same two candidates between them (or three cells hold three), those digits are spoken for. Erase them from every other cell of the unit.