The default calculator that comes bundled with Windows Mobile 6 isn’t made for touch phones. Also the application hasn’t received an upgrade from a long time. Even my 5 year old Casio Pocket PC is running the same calculator application !
gCalc is a simple calculator application which works great on a touch based phone and is also good for one-hand use. The operator dial pad saves you the trouble of searching operators while doing the calculations.
The user interface looks so much better compared to the dull interface of the default application. And if you are still not impressed by the UI, gCalc developer has made the application skinnable
gCalc with ClownFish Skin
The theme change has to be done using the About option ! You can find more details on gCalc here.