Step 1: Divide the number into separate digits:
2748 => 2 7 4 8
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
2 to 7 = 5
7 to 4 = 3
4 to 8 = 4
8 to 2 = 6
Step 3: Combine the filters to a string:
5 3 4 6 = 5346