Step 1: Divide the number into separate digits:
7302 => 7 3 0 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
7 to 3 = 4
3 to 0 = 3
0 to 2 = 2
2 to 7 = 5
Step 3: Combine the filters to a string:
4 3 2 5 = 4325