title: How to multiply 2 columns in 2 pandas data frames by each other
body: <p>I have 2 data frames like this </p>
  
  <pre><code>    DF1:    Col1 Col2
      Row1    A   30
      Row2    B   40
  
      DF2:  Col1 Col2
      Row1    A   10
      Row2    B   5
  </code></pre>
  
  <p>Now i want to multiply DF1.Col2 and DF2.Col2 and get an output like this</p>
  
  <pre><code>    Out:   Col1 COl3
      Row1    A   300
      Row2    B   200
  </code></pre>
  
  <p>How can I do this. I try bellow code but its not working</p>
  
  <pre><code>DF1[:,'Col3'] = pd.Series(DF1.Col2.astype(int)*DF2.Col2.astype(int),index=DF1.index)
  </code></pre>
  
  <p>This direct to bellow error:
  TypeError: unhashable type</p>