Step 1: Divide the number into separate digits:
5255 => 5 2 5 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 2 = 3
2 to 5 = 3
5 to 5 = 0
5 to 5 = 0
Step 3: Combine the filters to a string:
3 3 0 0 = 3300