3Ns and 3Ps

it might work, depending on what you're doing...

Usually if you're talking about something like this it's the first letter, not the last. So the second example is more correct. ("In this company, we always remember the three P's = Passion, Perseverance, and Professionalism.")

The three N's, with the N occuring at the end of the word, wouldn't happen.

3N's
Naughty, Nice, Neutral

Thanks RP and Sozobe.