Step 1: Divide the number into separate digits:
0672 => 0 6 7 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 6 = 6
6 to 7 = 1
7 to 2 = 5
2 to 0 = 2
Step 3: Combine the filters to a string:
6 1 5 2 = 6152