Fringe patterns caused by air film between two plates of glass?

Question

Assume that light of wavelength 532 nm strikes the top of two plates of glass nearly perpendicularly. The glass plates are in contact at one edge and separated by a thin sheet of paper at the other edge forming a narrow wedge of air between the two plates. The paper has a thickness of 4.10970×10-5 m. Determine the number of bright fringes that occur from the place where the plates touch to the edge of the sheet of paper.

I've tried the formula m= (2*thickness)/wavelength -.5. I got 154 and it didn't work.

Answer 1

There is a phase change of pi/2 at one of the reflective surfaces!