I assume that this is a partially-completed puzzle; it's always better to post the original grid as well as the point at which you gave become stuck. I don't know what level of help you are after but here's one hint:
Look in Box3 (the top, right box of nine cells).
The digits 4, 5, 7 and 9 can appear in any of four boxes but not in the remaining three:
- Code: Select all
124 6 49
1247 8 479
57 579 3
You can, thus, eliminate those digits from the other boxes to give:
- Code: Select all
12 6 49
12 8 479
57 579 3
The 1, 2 pairs in Box3 now allow you to eliminate those digits from the rest of Column7 etc.