title: Getting sum of int cells from multiple dataframes
body: <p>I have four dataframes with the same columns and a column "Area" which is consistent across the 4 dfs.</p>
  
  <pre><code>AREA     NUM1   NUM2
  london   10     10
  
  AREA     NUM1   NUM2
  london   5      5
  </code></pre>
  
  <p>The output which i want to see in my new data frame is</p>
  
  <pre><code>Area     NUM1   NUM2
  london   15     15
  </code></pre>
  
  <p>i have been try doing simple</p>
  
  <pre><code>dfTotal = df1 + df2
  </code></pre>
  
  <p>but what it is doing is giving me londonlondon for the area</p>