title: Grouping data with sum
body: <p>I have the following list:</p>
  
  <pre><code> mat.Add(new Material() { ID = 1, ProdName = "Cylinder", Weight=23, Discontinued='N'  });
   mat.Add(new Material() { ID = 2, ProdName = "Gas", Weight = 25, Discontinued='N' });
  mat.Add(new Material() { ID = 3, ProdName = "Match", Weight = 23, Discontinued='N' });
  </code></pre>
  
  <p>I want a result as:</p>
  
  <pre><code>2 Products have Weight 23 and Discontinued N
  1 Product have Weigth 25 Discontinued N
  </code></pre>