What number comes next in the following series? 63, 3, 44, 0, 91

What number comes next in the following series? 63, 3, 44, 0, 91

Explanation

It's a simple concept

63= 6–3=3

44= 4–4=0

91= 9–1=8

The series is 63,3,44,0,91,8