It's a calculator. But it is incomplete so don't expect it to be bug-free. Type in your equation with your keyboard or the buttons, then press =. It will then display your answer. To clear it, press C. To change between negative and positive numbers, press the -/+ button. If you find any bugs, please tell me in the comments. Oh and right now my calculator only does equations from left to right because its easier, I might add brackets and make it do the correct order later. I am using an ugly variable display for now because I can't figure out how to make a proper display. This took over 2 weeks to make.
