Step 1: Divide the number into separate digits:
06685 => 0 6 6 8 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 6 = 6
6 to 6 = 0
6 to 8 = 2
8 to 5 = 3
5 to 0 = 5
Step 3: Combine the filters to a string:
6 0 2 3 5 = 60235