Answer :

naǫ
If you fold a piece of paper, it will have 2 rectangles.
If you fold it again, it will have 4 rectangles.
If you fold it again, it will have 8 rectangles.
So, if you fold it n times, it will have 2^n rectangles.

[tex]2^n=128 \\ 2^n=2^7 \\ n=7[/tex]

If your paper has 128 rectangles, you made 7 folds.