Durofy

The answer is 12.85.

If the look as equiangular polygons, the various internal angles of polygons are :

Triangle - 60 (180/3)

Quadilateral - 90 (360/4)

Pentagon - 108 (540/5)

Hexagon - 120 (720/6)

Now, divide all of these by 10 - you get the given series. So the next number is (900/7) which is the internal angle of a Heptagon = 128.57 Further, dividing by 10 gives 12.85 which is the answer.