Step 1: Divide the number into separate digits:
79030 => 7 9 0 3 0
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
7 to 9 => 2
9 to 0 => 9
0 to 3 => 3
3 to 0 => 3
0 to 7 => 7
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
2 => N
9 => C
3 => N
3 => N
7 => N
Step 4: Combine the filters to a string:
N C N N N = NCNNN