Step 1: Divide the number into separate digits:
68138 => 6 8 1 3 8
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 8 = 2
8 to 1 = 7
1 to 3 = 2
3 to 8 = 5
8 to 6 = 2
Step 3: Combine the filters to a string:
2 7 2 5 2 = 27252