Step 1: Divide the number into separate digits:
4797 => 4 7 9 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
4 to 7 = 3
7 to 9 = 2
9 to 7 = 2
7 to 4 = 3
Step 3: Combine the filters to a string:
3 2 2 3 = 3223