Step 1: Divide the number into separate digits:
8327 => 8 3 2 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
8 to 3 = 5
3 to 2 = 1
2 to 7 = 5
7 to 8 = 1
Step 3: Combine the filters to a string:
5 1 5 1 = 5151