Step 1: Divide the number into separate digits:
8207 => 8 2 0 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
8 to 2 = 6
2 to 0 = 2
0 to 7 = 7
7 to 8 = 1
Step 3: Combine the filters to a string:
6 2 7 1 = 6271