Step 1: Divide the number into separate digits:
2766 => 2 7 6 6
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
2 to 7 = 5
7 to 6 = 1
6 to 6 = 0
6 to 2 = 4
Step 3: Combine the filters to a string:
5 1 0 4 = 5104