Step 1: Divide the number into separate digits:
78257 => 7 8 2 5 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
7 to 8 = 1
8 to 2 = 6
2 to 5 = 3
5 to 7 = 2
7 to 7 = 0
Step 3: Combine the filters to a string:
1 6 3 2 0 = 16320