Step 1: Divide the number into separate digits:
6789 => 6 7 8 9
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 7 = 1
7 to 8 = 1
8 to 9 = 1
9 to 6 = 3
Step 3: Combine the filters to a string:
1 1 1 3 = 1113