Step 1: Divide the number into separate digits:
6367 => 6 3 6 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 3 = 3
3 to 6 = 3
6 to 7 = 1
7 to 6 = 1
Step 3: Combine the filters to a string:
3 3 1 1 = 3311