FloatCalc is a simple, floating window for doing basic math problems.
It's display is large for easy reading and may be moved to any part of the desktop that is convenient for you.
It does the basics of math: addition, subtraction, multiplication and division. It can also recognize parentheses. Enter the equation or math in the box then hit enter.
Some keyboard shortcuts are also available without having to use the Command key: q quits the application, f brings it forward, k copies, p pastes, c clears, and h minimizes or hides the window. You can also use the buttons on the left of the window to do these same functions. In addition, the window provides a popup menu for memory, storage, clearing, and recalling.
Please read the documentation for more information.