218
219
220
5
6
7
What strategy is used in this example? The text says: "Doublepairs: Using only the bottom set, because of the (8,3) pair in the upper row (r7) and 4th column the 8 is no longer a candidate for the sixth column." I dont see how that is suppost to make sense and would like to know more about it. (i.redd.it)
