Step 1: Divide the number into separate digits:
44909 => 4 4 9 0 9
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
4 to 4 = 0
4 to 9 = 5
9 to 0 = 9
0 to 9 = 9
9 to 4 = 5
Step 3: Combine the filters to a string:
0 5 9 9 5 = 05995