I like math. I also like to use calculators; I don't mean for stuff like adding a few entries in my checkbook. I like entering in polynomials and other such fun equations into calculators. The fastest method is using reverse polish notation. Yes, that is really what it is called. While I like the reverse polish notation on many HP calculators, when I sit at a computer I prefer algebraic notation instead.
One calculator program that I like is Speedcrunch. It has a visual history, functions, a large constants library and all commands are accessible from the keyboard. The calculations are computed quickly and it takes very little system memory to run. Speedcrunch is available in many forms for varyious operating systems including Windows, GNU/Linux and MacOS.
I find two dissadvantages with speedcrunch. First, is that if you are using older versions of kde (3.5 or older) you will have to download an older version and possibly even compile it yourself. This is a very minor weakness. How many still use the older kde? I just happen to be one of those few.
The second disadvantage is that it is slow to open. This seems to be system independent as I use kde 4+, kde 3.5, windows XP and windows 7 and it is slow in all of those on at least 3 different hardware configurations.