Step 1: Divide the number into separate digits:
40256 => 4 0 2 5 6
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
4 to 0 = 4
0 to 2 = 2
2 to 5 = 3
5 to 6 = 1
6 to 4 = 2
Step 3: Combine the filters to a string:
4 2 3 1 2 = 42312