Step 1: Divide the number into separate digits:
33845 => 3 3 8 4 5
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
3 to 3 => 0
3 to 8 => 5
8 to 4 => 4
4 to 5 => 1
5 to 3 => 2
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
0 => E
5 => N
4 => N
1 => C
2 => N
Step 4: Combine the filters to a string:
E N N C N = ENNCN