i need interface and code to create the calculator.

What do you have so far? We do not provide ready solutions. Start, and if you have specific problems, ask.

I'm afraid we can't just give you a finished application.
Where's the fun in that?

All you need to do this is create a windows form with visual studio with buttons, and do some reasearch on basic mathematical functions in c# code.

Have a look at the 'getting started in c#' if you still need help.

You could also search DaniWeb. Contains lots of threads about calculators.

To make a simple calculator, just add buttons from 0-9, operation buttons (/,*,-,+) and equal (=) button. Use variables to store the numbers, then calculate it like how we do it on papers. Use your logic to finish your project and learned

You don t need daniweb for that, you ve got google...