Step 1: Divide the number into separate digits:
8008 => 8 0 0 8
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
8 to 0 = 8
0 to 0 = 0
0 to 8 = 8
8 to 8 = 0
Step 3: Combine the filters to a string:
8 0 8 0 = 8080