Step 1: Divide the number into separate digits:
6038 => 6 0 3 8
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 0 = 6
0 to 3 = 3
3 to 8 = 5
8 to 6 = 2
Step 3: Combine the filters to a string:
6 3 5 2 = 6352