title: How do I get DotNet Core 3.0 to recognize certain statements from DotNet Framework?
body: <p>I'm new to dotnet core and I'm trying to upgrade a project from VB.Net 2010 using dotnet framework 4.x to VB.Net 2019 using dotnet core 3.0.  Currently I'm just upgrading some user controls and the first two went fine, but the third one gives me an error with the statement </p>
  
  <p>MyBase.Text = FormatNumber(MyBase.Text, Decimals, TriState.True, TriState.False, ShowComma)</p>
  
  <p>It doesn't like the FormatNumber statement.</p>
  
  <p>In my old project I had some references to System, system.Core, system.Data, System.Drawing, system.windowsm.forms, System.XML,and system.XML.Linq via DLL's from the program files directory.  Are there dll's I should be referencing for dotnet core 3.0 to get reference to all of the namespaces.</p>
  
  <p>I have imported these namespaces, but I don't know how to reference them or even if I need to.</p>
  
  <p>Perhaps FormatNumber needs to be referenced by it's full namespace name, but I don't even know what that is.</p>
  
  <p>Any help would be appreciated.</p>
  
  <p>Thanks.</p>