Step 1: Divide the number into separate digits:
9965 => 9 9 6 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
9 to 9 = 0
9 to 6 = 3
6 to 5 = 1
5 to 9 = 4
Step 3: Combine the filters to a string:
0 3 1 4 = 0314