Solving Classic Sudoku: 'Hidden Pairs/Hidden Triplets'

This is just an extension of 'Naked Pairs/Naked Triplets'. If there are two (three) cells of a row/column which can take any one number of a pair (triplet) of numbers, then no other number can be placed in those two (three) cells.

Take a look at this Classic Sudoku below. Observe the 2nd and 7th columns, alongwith the 3rd row.


The 2nd column has two empty cells for '7' and '8'. The 7th column has three empty cells for '7', '8' and '9'.


All the possible candidates of every cell of the 3rd row is given. Observe R3C2 and R3C7 in the 3rd row.


'7' and '8' can be placed either in R3C2 or R3C7 in the 3rd row. Hence these two cells cannot have any other number. Hence R3C7 cannot be '9'. Using other '9's, the '9' in the 3rd box can be placed uniquely.

Other Solving Techniques