Step 1: Divide the number into separate digits:
15673 => 1 5 6 7 3
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
1 to 5 = 4
5 to 6 = 1
6 to 7 = 1
7 to 3 = 4
3 to 1 = 2
Step 3: Combine the filters to a string:
4 1 1 4 2 = 41142