Step 1: Divide the number into separate digits:
18141 => 1 8 1 4 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
1 to 8 = 7
8 to 1 = 7
1 to 4 = 3
4 to 1 = 3
1 to 1 = 0
Step 3: Combine the filters to a string:
7 7 3 3 0 = 77330