Step 1: Divide the number into separate digits:
1065 => 1 0 6 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
1 to 0 = 1
0 to 6 = 6
6 to 5 = 1
5 to 1 = 4
Step 3: Combine the filters to a string:
1 6 1 4 = 1614