Step 1: Divide the number into separate digits:
6808 => 6 8 0 8
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 8 = 2
8 to 0 = 8
0 to 8 = 8
8 to 6 = 2
Step 3: Combine the filters to a string:
2 8 8 2 = 2882