Step 1: Divide the number into separate digits:
32777 => 3 2 7 7 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
3 to 2 = 1
2 to 7 = 5
7 to 7 = 0
7 to 7 = 0
7 to 3 = 4
Step 3: Combine the filters to a string:
1 5 0 0 4 = 15004