I use it (Handycalc) often and it works well. I also downloaded DROID48 and found the (almost 700 pages) manual on the internet at http://www.educalc.net/217486.page. It looks a bit medieval, takes some time to learn how it works and resolution isn't great, but it really does a good job.

Handycalc doesn't do calculus. Therefore I use 'Calculus tools' (and since yesterday DROID48). But calculus tools does'nt work very well on the edge and it needs some upgrading work to make it a really good app. It's nice that apps are free or cost only a few dollars, but I would be willing to pay 10-20 times as much for a really good math application. Mabe that's too much money for an app used on a mobile phone, but the Edge is much more computer like and needs more sophisticated apps.