Step 1: Divide the number into separate digits:
71373 => 7 1 3 7 3
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
7 to 1 = 6
1 to 3 = 2
3 to 7 = 4
7 to 3 = 4
3 to 7 = 4
Step 3: Combine the filters to a string:
6 2 4 4 4 = 62444