Hello there! how are you doing? Can you please provide more details about the project? i have build many calculator using js and i can help you to complete yours as well so if the project is fairly paid I can build you a small part of it as form of a demo, afterwards you'll decide if you should hire me or not. Don't hesitate to contact me even though you might not be planing to hire me, I don't mind helping.
Regards Nadhir.B