These are features that are outisde the immediate math capabilities of CalcPad. For more information on features, look at the docs.
There are quite a few settings to choose from. You can autoload your last session, so you don't always have to save. You can change how the output looks, math conventions used in order of operations, and enable currency.
You can add custom functions, units, and constants. These are saved permenantly, so you don't have to keep putting them in.
There is a context menu with some useful features and keyboard shortcuts.