Step 1: Divide the number into separate digits:
0834 => 0 8 3 4
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 8 = 8
8 to 3 = 5
3 to 4 = 1
4 to 0 = 4
Step 3: Combine the filters to a string:
8 5 1 4 = 8514