Step 1: Divide the number into separate digits:
43205 => 4 3 2 0 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
4 to 3 = 1
3 to 2 = 1
2 to 0 = 2
0 to 5 = 5
5 to 4 = 1
Step 3: Combine the filters to a string:
1 1 2 5 1 = 11251