Step 1: Divide the number into separate digits:
6830 => 6 8 3 0
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 8 = 2
8 to 3 = 5
3 to 0 = 3
0 to 6 = 6
Step 3: Combine the filters to a string:
2 5 3 6 = 2536