Step 1: Divide the number into separate digits:
53984 => 5 3 9 8 4
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 3 => 2
3 to 9 => 6
9 to 8 => 1
8 to 4 => 4
4 to 5 => 1
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
2 => N
6 => N
1 => C
4 => N
1 => C
Step 4: Combine the filters to a string:
N N C N C = NNCNC