Step 1: Divide the number into separate digits:
3926 => 3 9 2 6
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
3 to 9 = 6
9 to 2 = 7
2 to 6 = 4
6 to 3 = 3
Step 3: Combine the filters to a string:
6 7 4 3 = 6743