title: C# double is cast as a string
body: <p>In C# I have the following code and I cant work out why my double values get rendered as a string?
  When I try to add Tax to Total it reverts to a string?</p>
  <pre><code>        double Total = 0;
          double Tax = 0;
  
          foreach (var Product in ProductList)
          {
              if (Product.Taxable)  Tax = Tax + (Product.Price * .1) ;
              Total = Total + (Product.Price * Product.Qty);
              Console.WriteLine(&quot;{0} {1} at {2}&quot;, Product.Qty, Product.Item, Product.Price.ToString(&quot;C&quot;), Product.Taxable, Product.Exempt);
          }
          Console.WriteLine(&quot;Sales Taxes: &quot; + Tax.ToString(&quot;C&quot;));            
          Console.WriteLine(&quot;Total: &quot; + Total.ToString(&quot;C&quot;));
          
          Console.WriteLine(&quot;Taxes: &quot; + Total + Tax);
  </code></pre>