alphabet

[bimbo123]

which letters of the alphabet are the same top and bottom

[Quizmonster]

Assuming you mean dividing the letters horizontally through their centres to create a 'top' and a 'bottom', I'd be tempted to say 'None of them'. The capital letter 'B' comes closest, in that it is almost like two capital letters 'D', one atop the other...ie they're the same. However, even it doesn't quite work, since one of the halves would have a thick topmost section whilst the other would have a thick bottom-most section. That's because the halving process would make the middle cross-bar thin...ie the bottom of the 'top' and the bottom of the 'bottom' are not identical!

[wildwood]

In the criteria as outlined by Quizmonster, the capital letter "I" must be in contention.

If you mean the same normal and upside down try "Z,I,H,N,O and X".

[xyzzy@bok]

Obviously, you need a sensible uppercase font for this to work; the letters are B C D E H I K O X ; Boats that have names made up of these letters cause a readable reflection in the water, names like; OAK, BEECH, ECHO etc. the longest words i can think of that do this are DIOXIDE, DECIDE, CHOICE, They are called alucardrums. A famous person with an alucardric is KIKI DEE, singer had seventies no.1 with Elton John. :-)