Step 1: Divide the number into separate digits:
0765 => 0 7 6 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 7 = 7
7 to 6 = 1
6 to 5 = 1
5 to 0 = 5
Step 3: Combine the filters to a string:
7 1 1 5 = 7115