title: add a row to the datatable so that it should display sum of amounts on the desired columns
body: <p>Hi all I am binding a <code>DataTable</code> to the <code>DataGridView</code> with some of the columns along with some amount fields.</p>
  
  <p>I need to show the sum of the columns for each of the amount filed in <code>DataGridView</code>. I have already searched for many options to add a footer to the <code>DataGridView</code>. Is there any possibility to sum up few columns in the <code>DataTable</code> so that I can display the data in <code>DataGridView</code>?</p>
  
  <p>This is my datatable data roughly:</p>
  
  <pre><code>  Name  Address   Amount   DiscountAmount
     XYZ   ABC       100.00         20.00
     ABC   DEF       150.00         0.00
  </code></pre>
  
  <p>Required result is:</p>
  
  <pre><code>  Name  Address   Amount   DiscountAmount
     XYZ   ABC       100.00         20.00
     ABC   DEF       150.00         0.00
                     250.00         20.00
  </code></pre>
  
  <p>I have already tried some thing like following - and it didn't worked:</p>
  
  <pre><code>DataRow lRow = lDTGrid.NewRow();
  lRow[0] = "Totals";
  for (int i = 1; i &lt; lDTGrid.Columns.Count; i++)
  {
    lRow[lDTGrid.Columns[i].ColumnName] = lDTGrid.Compute("Sum(" + lDTGrid.Columns[i].ColumnName + ")", "");
  }
  </code></pre>