Step 1: Divide the number into separate digits:
66729 => 6 6 7 2 9
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 6 = 0
6 to 7 = 1
7 to 2 = 5
2 to 9 = 7
9 to 6 = 3
Step 3: Combine the filters to a string:
0 1 5 7 3 = 01573