Methods of Calculation

My calculator uses two major components: The UI and the Calculator Engine (in progress, almost complete). The finished design will work like this: The UI takes care of all interactions between the user and the program. The Calculator Engine takes the numbers and computes them, and returns the result to the UI. The UI then prints the result on the display. This system makes use of the single responsibility principle. For a finished prototype of this system, see the calc_engine branch.