Step 1: Divide the number into separate digits:
9167 => 9 1 6 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
9 to 1 = 8
1 to 6 = 5
6 to 7 = 1
7 to 9 = 2
Step 3: Combine the filters to a string:
8 5 1 2 = 8512