Step 1: Divide the number into separate digits:
8780 => 8 7 8 0
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
8 to 7 = 1
7 to 8 = 1
8 to 0 = 8
0 to 8 = 8
Step 3: Combine the filters to a string:
1 1 8 8 = 1188