Step 1: Divide the number into separate digits:
06018 => 0 6 0 1 8
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 6 = 6
6 to 0 = 6
0 to 1 = 1
1 to 8 = 7
8 to 0 = 8
Step 3: Combine the filters to a string:
6 6 1 7 8 = 66178