Step 1: Divide the number into separate digits:
47489 => 4 7 4 8 9
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
4 to 7 => 3
7 to 4 => 3
4 to 8 => 4
8 to 9 => 1
9 to 4 => 5
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
3 => N
3 => N
4 => N
1 => C
5 => N
Step 4: Combine the filters to a string:
N N N C N = NNNCN