Step 1: Divide the number into separate digits:
5807 => 5 8 0 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 8 => 3
8 to 0 => 8
0 to 7 => 7
7 to 5 => 2
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
3 => N
8 => N
7 => N
2 => N
Step 4: Combine the filters to a string:
N N N N = NNNN