The basic idea is that there are sets of cells in any Sudoku grid that must contain the same collection of numbers,' says ...

Diagonal sudoku, for instance ... “Pairs” are two numbers that may go in two cells in either order — they can be “hidden” or “naked” depending on how identifiable they are.

A1)-1, 3) + 1 + MOD(ROW(Sudoku!A1)-1, 3) * 3 The above formula is used to map one cell from a 9x9 Sudoku grid to one of the positions within a smaller 3x3 sub-grid. In Sudoku the larger grid is ...