Step 1: Divide the number into separate digits:
88587 => 8 8 5 8 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
8 to 8 => 0
8 to 5 => 3
5 to 8 => 3
8 to 7 => 1
7 to 8 => 1
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
0 => E
3 => N
3 => N
1 => C
1 => C
Step 4: Combine the filters to a string:
E N N C C = ENNCC