Step 1: Divide the number into separate digits:
47685 => 4 7 6 8 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
4 to 7 => 3
7 to 6 => 1
6 to 8 => 2
8 to 5 => 3
5 to 4 => 1
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
3 => N
1 => C
2 => N
3 => N
1 => C
Step 4: Combine the filters to a string:
N C N N C = NCNNC