Step 1: Divide the number into separate digits:
91016 => 9 1 0 1 6
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
9 to 1 = 8
1 to 0 = 1
0 to 1 = 1
1 to 6 = 5
6 to 9 = 3
Step 3: Combine the filters to a string:
8 1 1 5 3 = 81153