title: How to get linq sum of IEnumerable<object>
body: <p>How do I get the sum of numbers that are in an IEnumerable collection of objects?  I know for sure that the underlying type will always be numeric but the type is determined at runtime.</p>
  
  <pre><code>IEnumerable&lt;object&gt; listValues = data.Select(i =&gt; Convert.ChangeType(property.GetValue(i, null), columnType));
  </code></pre>
  
  <p>After that I want to be able to do the following (the following has the error:"Cannot resolve method Sum"):</p>
  
  <pre><code>var total = listValues.Sum();
  </code></pre>
  
  <p>Any ideas? Thank you.</p>