title: How to make a formula to sum values by month?
body: <p>I have a database with products ordered by day. How do I make an excel formula to sum the values by month so that autofill sums each month when I drag down?
  I want this formula in a different sheet and I cannot make any more columns in this sheet. 
  Example:</p>
  
  <pre><code>Col A       Col B
  5/1/2014    411
  5/2/2014    332
  5/3/2014    247
  5/4/2014    369
  5/5/2014    780
  5/6/2014    577
  5/7/2014    653
  5/8/2014    848
  5/9/2014    925
  5/10/2014   911
  5/11/2014   444
  5/12/2014   327
  5/13/2014   440
  5/14/2014   503
  5/15/2014   613
  5/16/2014   753
  5/17/2014   875
  5/18/2014   404
  5/19/2014   628
  5/20/2014   776
  5/21/2014   829
  5/22/2014   505
  5/23/2014   515
  5/24/2014   703
  5/25/2014   511
  5/26/2014   747
  5/27/2014   707
  5/28/2014   782
  5/29/2014   101
  5/30/2014   113
  5/31/2014   283
  </code></pre>