There are two ways to find this 2.
The arrows in rows 6 and 8 show that 2's already exist in those rows. So the only place left for a 2 in column 6 is in row 7.
Column 6 still needs 279. There is already a 7 and a 9 in row 7. Therefore a 2 is the only number that will fit here.
<< Back to challenges pageSudoku - the puzzle that addicts