Step 1: Divide the number into separate digits:
71431 => 7 1 4 3 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
7 to 1 = 6
1 to 4 = 3
4 to 3 = 1
3 to 1 = 2
1 to 7 = 6
Step 3: Combine the filters to a string:
6 3 1 2 6 = 63126