Step 1: Divide the number into separate digits:
07823 => 0 7 8 2 3
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 7 => 7
7 to 8 => 1
8 to 2 => 6
2 to 3 => 1
3 to 0 => 3
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
7 => N
1 => C
6 => N
1 => C
3 => N
Step 4: Combine the filters to a string:
N C N C N = NCNCN