title: Pandas how to keep the LAST trailing zeros when exporting DataFrame into CSV
body: <p>In this question, my goal is to preserve the <strong>last</strong> <strong>trailing</strong> <code>zeros</code> when exporting the <code>DataFrame</code> to <code>CSV</code></p>
  
  <p>My <code>dataset</code> looks like this:</p>
  
  <pre><code>EST_TIME    Open    High
  2017-01-01  1.0482  1.1200    
  2017-01-02  1.0483  1.1230
  2017-01-03  1.0485  1.0521
  2017-01-04  1.0480  1.6483
  2017-01-05  1.0480  1.7401
  ...., ...., ....
  2017-12-31  1.0486  1.8480
  </code></pre>
  
  <p>I import and create a DataFrame and save to CSV by doing this:</p>
  
  <pre><code>df_file = '2017.csv'
  df.to_csv(df_file, index=False)
  files.download(df_file)
  </code></pre>
  
  <p>When I view the CSV, I see this:</p>
  
  <pre><code>EST_TIME    Open    High
  2017-01-01  1.0482  1.12   
  2017-01-02  1.0483  1.123
  2017-01-03  1.0485  1.0521
  2017-01-04  1.048   1.6483
  2017-01-05  1.048   1.7401
  ...., ...., ....
  2017-12-31  1.0486  1.848
  </code></pre>
  
  <p>All the zeros at the end are gone. I want to preserve the trailing zeros when I save the CSV and I want it at 4 decimal place.</p>
  
  <p>Could you please let me know how can I achieve this?</p>