Step 1: Divide the number into separate digits:
57187 => 5 7 1 8 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 7 = 2
7 to 1 = 6
1 to 8 = 7
8 to 7 = 1
7 to 5 = 2
Step 3: Combine the filters to a string:
2 6 7 1 2 = 26712