https://adtmag.com/articles/2019/03/06/open-source-calculator.aspx

Microsoft has open sourced the code for its Windows Calculator app, inviting developers to help improve the tool's user experience while at the same time learning about and possibly adopting its technological underpinnings.

While the underpinnings of a "simple" calculator app might seem trivial compared to major enterprise development projects, Microsoft said using the app's open source code can help them learn many different things.