> Oh, okay. I've noticed an interesting thing about [] though -- it is
> almost as slow as doing a " % 2" on the number!

Fortunately, I'll only ever be playing with relatively small numbers, so 
the speed isn't an issue for me.  However, it sounds like there's an 
opportunity for a cleanup on the [] method for BigNum.

Strangely, I just tried writing a tiny two line routine to get the parity 
and it performs only slightly better than using Ruby's & and is still not 
as fast as [], which I find bizarre, since it's a cut-down version of the 
code for [] !!

Oh well. Someone's bound to come back and tell you how to make things 
faster.

Thanks again for the code snippet.