title: how to aggregate decimal with Linq
body: <p>I try to </p>
  
  <pre><code>Collection.Aggregate(0.0,(current, next) =&gt; current += next.decimalValue);
  </code></pre>
  
  <p>but I get error of casting decimal to double</p>
  
  <p>another issue: For "Sum" Linq the seed is the default type value?
  meaning seed = 0 for decimal...</p>