Step 1: Divide the number into separate digits:
0507 => 0 5 0 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 5 = 5
5 to 0 = 5
0 to 7 = 7
7 to 0 = 7
Step 3: Combine the filters to a string:
5 5 7 7 = 5577