Step 1: Divide the number into separate digits:
4923 => 4 9 2 3
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
4 to 9 = 5
9 to 2 = 7
2 to 3 = 1
3 to 4 = 1
Step 3: Combine the filters to a string:
5 7 1 1 = 5711