Step 1: Divide the number into separate digits:
2278 => 2 2 7 8
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
2 to 2 = 0
2 to 7 = 5
7 to 8 = 1
8 to 2 = 6
Step 3: Combine the filters to a string:
0 5 1 6 = 0516