Desktop calculators aren't that hard to find. And each version has its own unique features. What I like best about Calc98 - Version 4.5 (and it's earlier versions) is the great program it has for CONVERSIONS. I can't think of a single field of study that isn't represented in the list of conversions, as long as the elements of interest are quantifiable. It's a fine calculator in itself, but I find myself relying on it more for its massive conversion capabilities. By description, it's a Scientific Engineering Financial Calculator (and a more complete description is contained at the download link given below).
Calc98 Version 4.5 is a free download and a quick and easy install. If you ever need to go from square millimeters to acres or microns to parsecs, or visa verse, Calc98 makes it a breeze.
Calc98 Version 5.28 Beta Release is available Flow Simulation Ltd. (user:beta, password:Argand) for your review.
I think if I'd have had access to this from high school onward, I'd not only have gotten more of my homework right, I'd have a much better understanding of the relationship between mathematical measurements. But I'm still stumped on how many square widgahoosers there are in a Grand Kiloflex.