2 1 _ 8 _ _ 4 7 5
8 7 _ 5 4 1 2 _ 9
4 9 5 7 2 _ 1 _ 8
9 6 4 3 1 5 8 2 7
3 5 2 6 7 8 9 4 1
7 8 1 4 9 2 3 5 6
6 2 9 1 3 7 5 8 4
5 3 7 9 8 4 6 1 2
1 4 8 2 _ _ 7 9 3
There is only one way to fill in the squares that I've filled in. (unless I've made a logical error... in which case there is a small possibility that there are more.) However, there are three different ways you can complete this puzzle.