Step 1: Divide the number into separate digits:
6812 => 6 8 1 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 8 = 2
8 to 1 = 7
1 to 2 = 1
2 to 6 = 4
Step 3: Combine the filters to a string:
2 7 1 4 = 2714