Step 1: Divide the number into separate digits:
10874 => 1 0 8 7 4
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
1 to 0 = 1
0 to 8 = 8
8 to 7 = 1
7 to 4 = 3
4 to 1 = 3
Step 3: Combine the filters to a string:
1 8 1 3 3 = 18133