Step 1: Divide the number into separate digits:
6934 => 6 9 3 4
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 9 = 3
9 to 3 = 6
3 to 4 = 1
4 to 6 = 2
Step 3: Combine the filters to a string:
3 6 1 2 = 3612