Step 1: Divide the number into separate digits:
4568 => 4 5 6 8
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
4 to 5 = 1
5 to 6 = 1
6 to 8 = 2
8 to 4 = 4
Step 3: Combine the filters to a string:
1 1 2 4 = 1124