title: Sum only values which fall Monday to Friday
body: <p>I receive a statement (as a .xls) each month which list a bunch billable items with an associated date. I want to create a formula (using either <code>=sum()</code> or <code>=sumifs()</code> to total the billable items, but only those which fall Monday to Friday (i.e., not weekends). Is that possible?</p>
  
  <pre><code>              A             B
  ------+--------------+-------------
     1  |  05/12/2016  |   $10.00
     2  |  06/12/2016  |   $10.00
     3  |  07/12/2016  |   $10.00
     4  |  08/12/2016  |   $10.00        dates are formatted as
     5  |  09/12/2016  |   $10.00              dd/mm/yyyy
     6  |  10/12/2016  |   $10.00
     7  |  11/12/2016  |   $10.00
     8  |  12/12/2016  |   $10.00
  ------+--------------+-------------
        |     Sum      |   $80.00
  ------+--------------+-------------
        |     Sum      |
        | (no weekends)|   $60.00
  ------+--------------+-------------
  </code></pre>
  
  <p>EDIT:
  I've just looked closer at the excel doc, and it's actually a datetime field, e.g. 31/10/2016  12:44:00 pm (displayed as 31/10/16 12:44).</p>
  
  <p>I'm also not looking for a formula which works line by line, I'd like something which I can just copy and paste into a single cell at the bottom of the doc each month which examines <code>A:A</code>. </p>