Step 1: Divide the number into separate digits:
93809 => 9 3 8 0 9
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
9 to 3 = 6
3 to 8 = 5
8 to 0 = 8
0 to 9 = 9
9 to 9 = 0
Step 3: Combine the filters to a string:
6 5 8 9 0 = 65890