Step 1: Divide the number into separate digits:
5671 => 5 6 7 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 6 = 1
6 to 7 = 1
7 to 1 = 6
1 to 5 = 4
Step 3: Combine the filters to a string:
1 1 6 4 = 1164