Step 1: Divide the number into separate digits:
5748 => 5 7 4 8
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 7 = 2
7 to 4 = 3
4 to 8 = 4
8 to 5 = 3
Step 3: Combine the filters to a string:
2 3 4 3 = 2343