Step 1: Divide the number into separate digits:
3300 => 3 3 0 0
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
3 to 3 = 0
3 to 0 = 3
0 to 0 = 0
0 to 3 = 3
Step 3: Combine the filters to a string:
0 3 0 3 = 0303