Step 1: Divide the number into separate digits:
50047 => 5 0 0 4 7
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 0 => 5
0 to 0 => 0
0 to 4 => 4
4 to 7 => 3
7 to 5 => 2
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
5 => N
0 => E
4 => N
3 => N
2 => N
Step 4: Combine the filters to a string:
N E N N N = NENNN