Step 1: Divide the number into separate digits:
98151 => 9 8 1 5 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
9 to 8 = 1
8 to 1 = 7
1 to 5 = 4
5 to 1 = 4
1 to 9 = 8
Step 3: Combine the filters to a string:
1 7 4 4 8 = 17448