Step 1: Divide the number into separate digits:
04787 => 0 4 7 8 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 4 = 4
4 to 7 = 3
7 to 8 = 1
8 to 7 = 1
7 to 0 = 7
Step 3: Combine the filters to a string:
4 3 1 1 7 = 43117