Step 1: Divide the number into separate digits:
87905 => 8 7 9 0 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
8 to 7 = 1
7 to 9 = 2
9 to 0 = 9
0 to 5 = 5
5 to 8 = 3
Step 3: Combine the filters to a string:
1 2 9 5 3 = 12953