Step 1: Divide the number into separate digits:
3352 => 3 3 5 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
3 to 3 = 0
3 to 5 = 2
5 to 2 = 3
2 to 3 = 1
Step 3: Combine the filters to a string:
0 2 3 1 = 0231