Step 1: Divide the number into separate digits:
65515 => 6 5 5 1 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 5 = 1
5 to 5 = 0
5 to 1 = 4
1 to 5 = 4
5 to 6 = 1
Step 3: Combine the filters to a string:
1 0 4 4 1 = 10441