title: Conditionally get the sum from a list
body: <p>I have a class PropertyDetails:</p>
  
  <pre><code>public class PropertyDetails 
  {      
      public int Sequence { get; set; } 
  
      public int Length { get; set; }   
  
      public string Type { get; set; } 
  } 
  </code></pre>
  
  <p>I am creating a list of PropertyDetails as </p>
  
  <pre><code>List&lt;PropertyDetails&gt; propertyDetailsList = new List&lt;PropertyDetails&gt;();
  </code></pre>
  
  <p>I want the sum of <code>Length</code> from the list where <code>PropertyDetails.Sequence</code> &lt; sumValue=4</p>
  
  <p>Linq solutions are welcome.</p>