Due to the scarcity of N*000 numbers, we sometimes offer numbers that use 'Q' to  view as 0.. as in the Falcon 9000 registration pictured here (N900Q)
Q's
&
0s
K's
&
Xs
N75EK
The same applies to numbers that have Ks to view as Xs. With a clever choice of FAA approved fonts and placed strategically, they can look excellent to the casual observer and are great value at about a fifth to a tenth the price of numbers using  real X's. I saw the Global Express s/n 9108 at KVNY, it had the registration N700EK [for 700EXpress] very nicely done, but so far I haven't been able to find a photo of it. If anyone has one, please send it in, I'd appreciate it.
8's and B's are almost identical as seen here on this Bell 429
B's
&
8s
S's
&
5s
The number 5 and the letter S are almost indistinguishable,  as apparent in this image below.
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