Here is command I used initially:
nunit-console /framework:net-4.0 /run:NUnit_Application.Test.TestClass.AddTest C:~\NUnit_Application\NUnit_Application\NUnit_Application.Test\bin\Debug\NUnit_Application.Test.dll /include:"MathA"
I noticed if I just call TestClass and not the individual test case, it works:
nunit-console /framework:net-4.0 /run:NUnit_Application.Test.TestClass C:~\NUnit_Application\NUnit_Application\NUnit_Application.Test\bin\Debug\NUnit_Application.Test.dll /include:"MathA"