Step 1: Divide the number into separate digits:
78142 => 7 8 1 4 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
7 to 8 = 1
8 to 1 = 7
1 to 4 = 3
4 to 2 = 2
2 to 7 = 5
Step 3: Combine the filters to a string:
1 7 3 2 5 = 17325