Step 1: Divide the number into separate digits:
7860 => 7 8 6 0
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
7 to 8 = 1
8 to 6 = 2
6 to 0 = 6
0 to 7 = 7
Step 3: Combine the filters to a string:
1 2 6 7 = 1267