bigCalc

bigCalc is a simple program that enables you to perform basic calculations on your Mac. This application brings you a straightforward interface with large sized buttons and display.
To be honest, the only purpose I see for developing a Mac calculator of this size is that it's designed for users with vision problems.

The default Mac calculator has a small window and tiny buttons for symbols and functions that can't be enlarged for a clearer view.

More to that, bigCalc has a very small number of math functions and symbols and can be used only for basic mathematical calculations. You can't undo any wrongfully typed symbols or copy the results to clipboard to use them in other applications. The program only lets you print the results.

My guess is that this software is suitable for users who only need to make home budget calculations. Therefore, if you're looking for an advanced calculator, I advise you to look for other programs. bigCalc can only perform basic equations and offers you a very small number of math functions.