Step 1: Divide the number into separate digits:
6141 => 6 1 4 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 1 = 5
1 to 4 = 3
4 to 1 = 3
1 to 6 = 5
Step 3: Combine the filters to a string:
5 3 3 5 = 5335