Step 1: Divide the number into separate digits:
09163 => 0 9 1 6 3
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 9 => 9
9 to 1 => 8
1 to 6 => 5
6 to 3 => 3
3 to 0 => 3
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
9 => C
8 => N
5 => N
3 => N
3 => N
Step 4: Combine the filters to a string:
C N N N N = CNNNN