Step 1: Divide the number into separate digits:
7585 => 7 5 8 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
7 to 5 = 2
5 to 8 = 3
8 to 5 = 3
5 to 7 = 2
Step 3: Combine the filters to a string:
2 3 3 2 = 2332