Where is my System.Numerics namespace?

I'm using Visual Studio 2010 and trying to use the BigInteger type in a C# program. This type is supposed to be available in System.Numerics namespace, but I don't seem to have that installed in the .Net 4.0 framework. When I type "using System.Numerics;" in VS2010, a red underline appears under the "Numerics". Has anyone else ever had this problem?

If so, how do you resolve it? I just re-downloaded and re-installed (repaired) the .Net 4.0 framework, but that didn开发者_高级运维't help. I've never had any problems with other C# programs that I've written, so I'm wondering what I'm missing.

You need to add an assembly reference to System.Numerics.dll

The MSDN entry on BigInteger states:

BigInteger Structure
...
Namespace: System.Numerics
Assembly: System.Numerics (in System.Numerics.dll)

Though most assemblies are the part of the installation, VS does add only some core elements to the reference list of a project (Core, Data, XML etc.). One needs to add other references by hand using Reference Manager.

Right-click your project, then select Add Reference (or Add->Reference). System.Numerics resides in Assemblies. Then you can use using System.Numerics; in project files.

PS: this answer is not intended to get any vote. It is only for future reference if someone needs how to do it, just as I needed before this answer.