Step 1: Divide the number into separate digits:
87481 => 8 7 4 8 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
8 to 7 = 1
7 to 4 = 3
4 to 8 = 4
8 to 1 = 7
1 to 8 = 7
Step 3: Combine the filters to a string:
1 3 4 7 7 = 13477