I'm thinking about building a calculator with a PIC for educational
purposes.  I was hoping that people could give me their thoughts on a few
points ( some of which are a bit off-topic [ you've been warned ] )...

1) I guess I'm looking for a collection of math routines.  I've run
across a few on the web, but what eludes me is the theory of dealing with
numbers bigger than 0xFF.

2) LCD vs LED screen.  I'd like to go with a LCD, but I don't know if you
can get small pic friendly LCDs.  They all seem big.

Well I guess there really weren't any points, I was just hoping to hear a
few peoples thoughts on what aproach they'd take.  Is it reasonable to try
and make it a solar calculator?  How much code space would you guess I'd
use.  What kind of keypad?  Any dialogue on this subject (hardware and
software) would be welcomed (and beneficial to me).

Thanks,
Nathan Hendler