Step 1: Divide the number into separate digits:
86009 => 8 6 0 0 9
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
8 to 6 => 2
6 to 0 => 6
0 to 0 => 0
0 to 9 => 9
9 to 8 => 1
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
2 => N
6 => N
0 => E
9 => C
1 => C
Step 4: Combine the filters to a string:
N N E C C = NNECC