This project using Altera Quartus 2 Version 9.0 software. I'm showing you the unfinished calculator basic design using some basic logic gates. . This design is for 8 inputs calculator only. You may change it with more inputs or output and completed it on your own efforts.
Addition
> the close up view on the input; 1st two chips
>the close up view on the output
Subtract
> the close up view on the input;...
