Step 1: Divide the number into separate digits:
48015 => 4 8 0 1 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
4 to 8 => 4
8 to 0 => 8
0 to 1 => 1
1 to 5 => 4
5 to 4 => 1
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
4 => N
8 => N
1 => C
4 => N
1 => C
Step 4: Combine the filters to a string:
N N C N C = NNCNC