Step 1: Divide the number into separate digits:
05503 => 0 5 5 0 3
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 5 = 5
5 to 5 = 0
5 to 0 = 5
0 to 3 = 3
3 to 0 = 3
Step 3: Combine the filters to a string:
5 0 5 3 3 = 50533