Step 1: Divide the number into separate digits:
18288 => 1 8 2 8 8
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
1 to 8 = 7
8 to 2 = 6
2 to 8 = 6
8 to 8 = 0
8 to 1 = 7
Step 3: Combine the filters to a string:
7 6 6 0 7 = 76607