Step 1: Divide the number into separate digits:
67057 => 6 7 0 5 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 7 = 1
7 to 0 = 7
0 to 5 = 5
5 to 7 = 2
7 to 6 = 1
Step 3: Combine the filters to a string:
1 7 5 2 1 = 17521