title: How do I ignore cell references that contain text when performing calculations?
body: <p>For instance I am trying to use a very simple formula, like so:</p>
  
  <pre><code>=(B1+C1+D1+E1)/4
  </code></pre>
  
  <p>Now let's say that cells B1 &amp; D1 contains the numbers 201, 301 respectively. Let's say that cells C1 &amp; E 1 contain the text "-". Now when I attempt to run the calculation I'm given the following error: </p>
  
  <pre><code>#VALUE
  </code></pre>
  
  <p>How can have the formula ignore the text and only perform calculations on the cells that contain numbers? </p>