Step 1: Divide the number into separate digits:
8847 => 8 8 4 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
8 to 8 => 0
8 to 4 => 4
4 to 7 => 3
7 to 8 => 1
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
0 => E
4 => N
3 => N
1 => C
Step 4: Combine the filters to a string:
E N N C = ENNC