Step 1: Divide the number into separate digits:
83870 => 8 3 8 7 0
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
8 to 3 = 5
3 to 8 = 5
8 to 7 = 1
7 to 0 = 7
0 to 8 = 8
Step 3: Combine the filters to a string:
5 5 1 7 8 = 55178