 <p>The <code>Aggregate</code> function would come in handy here.</p> <pre><code>var sum = list.Aggregate((acc, cur) =&gt; acc + cur); var average = list.Aggregate((acc, cur) =&gt; acc + cur) / list.Count; </code></pre> <p>Just insure that you have the <code>/</code> operator defined for types <code>PointD</code> and <code>int</code>, and this should do the job.</p> <p>Note: I'm not quite sure whether you want the sum or average here (your question is somewhat ambiguous about this), but I've included examples for both.</p>