Step 1: Divide the number into separate digits:
66865 => 6 6 8 6 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 6 = 0
6 to 8 = 2
8 to 6 = 2
6 to 5 = 1
5 to 6 = 1
Step 3: Combine the filters to a string:
0 2 2 1 1 = 02211