Step 1: Divide the number into separate digits:
4384 => 4 3 8 4
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
4 to 3 = 1
3 to 8 = 5
8 to 4 = 4
4 to 4 = 0
Step 3: Combine the filters to a string:
1 5 4 0 = 1540