Step 1: Divide the number into separate digits:
3270 => 3 2 7 0
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 0 = 7
0 to 3 = 3
Step 3: Combine the filters to a string:
1 5 7 3 = 1573