Step 1: Divide the number into separate digits:
26355 => 2 6 3 5 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
2 to 6 = 4
6 to 3 = 3
3 to 5 = 2
5 to 5 = 0
5 to 2 = 3
Step 3: Combine the filters to a string:
4 3 2 0 3 = 43203