Step 1: Divide the number into separate digits:
5667 => 5 6 6 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 6 = 1
6 to 6 = 0
6 to 7 = 1
7 to 5 = 2
Step 3: Combine the filters to a string:
1 0 1 2 = 1012