Step 1: Divide the number into separate digits:
3725 => 3 7 2 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
3 to 7 = 4
7 to 2 = 5
2 to 5 = 3
5 to 3 = 2
Step 3: Combine the filters to a string:
4 5 3 2 = 4532