---
languages:
- vb
products:
- dotnet
page_type: sample
name: "MEF Sample: Simple Calculator (Visual Basic)"
urlFragment: "simple-calculator-vb"
description: "A .NET Core console application that contains the example method from Simple Calculator MEF Application in Visual Basic."
---

# MEF Sample: Simple Calculator (Visual Basic)

The simplest way to see what Managed Extensibility Framework can do is to build a simple MEF application. In this example, you build a very simple calculator named SimpleCalculator. The goal of SimpleCalculator is to create a console application that accepts basic arithmetic commands, in the form "5+3" or "6-2", and returns the correct answers. Using MEF, you will be able to add new operators without changing the application code.

NOTE: The purpose of SimpleCalculator is to demonstrate the concepts and syntax of MEF, rather than to necessarily provide a realistic scenario for its use. Many of the applications that would benefit most from the power of MEF are more complex than SimpleCalculator. For more extensive examples, see [Managed Extensibility Framework](https://github.com/MicrosoftArchive/mef) samples.

## Building the sample

To download and run the sample, follow these steps:

1. Download and unzip the sample.

2. In Visual Studio 2019 or later:

    1. On the menu bar, choose **File** > **Open** > **Project/Solution**.

    2. Navigate to the folder that holds the unzipped sample code, and open the solution (*.sln*) file.

    3. Press <kbd>F5</kbd> or <kbd>Ctrl</kbd>+<kbd>F5</kbd> to run the project.

3. From the command line:

    1. Navigate to the folder that holds the unzipped sample code.

    2. At the command line, type `dotnet run`.

## More information

- <https://docs.microsoft.com/dotnet/framework/mef/>