Step 1: Divide the number into separate digits:
9056 => 9 0 5 6
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
9 to 0 = 9
0 to 5 = 5
5 to 6 = 1
6 to 9 = 3
Step 3: Combine the filters to a string:
9 5 1 3 = 9513