Hidden Subsets

If two missing digits can each go in only the same two cells of a row, column or block, those cells must contain that pair. Remove every other candidate from the two cells. Learn to spot Hidden Pairs with and without pencil notes, and use the eliminations to reveal Hidden Singles.

Find three missing digits whose only possible positions in a row, column or block lie in three cells. Reserve those cells for the three digits and remove every other candidate from them. The digits need not appear in all three cells. Follow the pencil-note examples and interactive demo, then practice with prepared library puzzles.