The code sample demonstrates a standard calculator app in Windows 10 Universal Windows Platform. Its functionality is almost identical to the built-in Standard Calculator app in Windows 10.
Code Sample Download: http://scottge.net/product/uwp-windows-10-sample-calculator/ (The code sample has high quality, and I maintain it constantly. Please feel free to leave your technical questions in the sample download page. I will help you.)
After you download the sample, you will get the complete source code to debug and run. The code sample can be easily extended to support more advanced functions