In Windows 10, Microsoft replaced the good old calculator with a new Modern app. Recently, the app got a revamped user interface with the Fluent Design bits applied. Microsoft also updated the app with a new feature: the Calculator got a built-in currency converter!
You might have noticed that in the leaked Windows 10 build 9901, Microsoft killed the good old calculator in favor of its Modern (Metro) version. Even when you type "calc.exe" into the Run box, the Modern app will open. Here is an explanation of why this happens. I will also show you an alternative way to run the Modern Calculator app directly since you have no choice anyway.