Step 1: Divide the number into separate digits:
57886 => 5 7 8 8 6
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 7 = 2
7 to 8 = 1
8 to 8 = 0
8 to 6 = 2
6 to 5 = 1
Step 3: Combine the filters to a string:
2 1 0 2 1 = 21021