Step 1: Divide the number into separate digits:
65602 => 6 5 6 0 2
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 5 => 1
5 to 6 => 1
6 to 0 => 6
0 to 2 => 2
2 to 6 => 4
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
1 => C
1 => C
6 => N
2 => N
4 => N
Step 4: Combine the filters to a string:
C C N N N = CCNNN