When a certain pair of numbers are found only in two cells of a UNIT, the other numbers in these cells can be excluded.
Example in a row: In the Sudoku below, the numbers “1” and “8” are only found in row F, in cells F4 and F7, therefore, the other numbers in THESE TWO CELLS can be excluded:
Example in a column: in column 6, the numbers “6” and “9” are only present in cells C6 and G6, the numbers in red can be excluded:
Example in a box: In Box 1, the numbers “1” and “8” are only present in cells A2 and A3, the numbers “2” and “5” can be excluded:
Tip: with the elimination, one can also eliminate the number “1” in cell A7, due to the “new” pair (1,8) formed in cells A2 and A3. Always observe the next consequence of a decision made.
