Step 1: Divide the number into separate digits:
84689 => 8 4 6 8 9
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
8 to 4 = 4
4 to 6 = 2
6 to 8 = 2
8 to 9 = 1
9 to 8 = 1
Step 3: Combine the filters to a string:
4 2 2 1 1 = 42211