Step 1: Divide the number into separate digits:
0928 => 0 9 2 8
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 9 = 9
9 to 2 = 7
2 to 8 = 6
8 to 0 = 8
Step 3: Combine the filters to a string:
9 7 6 8 = 9768