Step 1: Divide the number into separate digits:
1178 => 1 1 7 8
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
1 to 1 = 0
1 to 7 = 6
7 to 8 = 1
8 to 1 = 7
Step 3: Combine the filters to a string:
0 6 1 7 = 0617