Step 1: Divide the number into separate digits:
3255 => 3 2 5 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
3 to 2 = 1
2 to 5 = 3
5 to 5 = 0
5 to 3 = 2
Step 3: Combine the filters to a string:
1 3 0 2 = 1302