1) that is a method, but not the one I used. This one has been already solved by tdig
2) that method works. however, look at the spoiler i gave framm before your post.
3) Yes there can be many methods. MY method is different from +1. that's all im trying to say. You're answer is right.
4) Yes.
WHAT HAS BEEN SOLVED:
1) 5 16 38 82 _?_ - SOLVED
2) 2 22 24 44 _?_ - Answer's here, but not my method
3) 15 16 17 18 _?_ (No, It's not, +1) - Answer's here, but not my method
4) 16 14 13 12-and-a-half _?_ - SOLVED