title: How to replace space with a digit in middle of the mobile number
body: <p>I have a data frame with column name as "Mobile No".Few of the entries are having space in the 6th position which ends up 9 digit number.</p>
  
  <p>Would like to replace space in 6th position with a digit(8) to make 10 digit number. please suggest.</p>
  
  <p>Before applying below code have ensured, no 'NaN's in df["Mobile No"] column and code was run. After running its df["Mobile No"] filled with 'NaN's.
  Looks like something isn't working. </p>
  
  <pre><code>df["Mobile No"] = df["Mobile No"].str.replace('  ', ' ')
  Sample number with space in '88888 8888'
  </code></pre>