Step 1: Divide the number into separate digits:
8552 => 8 5 5 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
8 to 5 = 3
5 to 5 = 0
5 to 2 = 3
2 to 8 = 6
Step 3: Combine the filters to a string:
3 0 3 6 = 3036