Step 1: Divide the number into separate digits:
9350 => 9 3 5 0
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
9 to 3 = 6
3 to 5 = 2
5 to 0 = 5
0 to 9 = 9
Step 3: Combine the filters to a string:
6 2 5 9 = 6259