Step 1: Divide the number into separate digits:
31758 => 3 1 7 5 8
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
3 to 1 = 2
1 to 7 = 6
7 to 5 = 2
5 to 8 = 3
8 to 3 = 5
Step 3: Combine the filters to a string:
2 6 2 3 5 = 26235