Step 1: Divide the number into separate digits:
1711 => 1 7 1 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
1 to 7 = 6
7 to 1 = 6
1 to 1 = 0
1 to 1 = 0
Step 3: Combine the filters to a string:
6 6 0 0 = 6600