Step 1: Divide the number into separate digits:
91432 => 9 1 4 3 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
9 to 1 = 8
1 to 4 = 3
4 to 3 = 1
3 to 2 = 1
2 to 9 = 7
Step 3: Combine the filters to a string:
8 3 1 1 7 = 83117