Step 1: Divide the number into separate digits:
10879 => 1 0 8 7 9
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
1 to 0 = 1
0 to 8 = 8
8 to 7 = 1
7 to 9 = 2
9 to 1 = 8
Step 3: Combine the filters to a string:
1 8 1 2 8 = 18128