Step 1: Divide the number into separate digits:
14520 => 1 4 5 2 0
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
1 to 4 = 3
4 to 5 = 1
5 to 2 = 3
2 to 0 = 2
0 to 1 = 1
Step 3: Combine the filters to a string:
3 1 3 2 1 = 31321