Step 1: Divide the number into separate digits:
1583 => 1 5 8 3
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
1 to 5 = 4
5 to 8 = 3
8 to 3 = 5
3 to 1 = 2
Step 3: Combine the filters to a string:
4 3 5 2 = 4352