Step 1: Divide the number into separate digits:
8304 => 8 3 0 4
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
8 to 3 = 5
3 to 0 = 3
0 to 4 = 4
4 to 8 = 4
Step 3: Combine the filters to a string:
5 3 4 4 = 5344