title: Formula to find last blank cell in a range
body: <p>I need to create a formula that returns the row number of the last empty cell within a range.  For example</p>
  
  <pre><code>Cell   Data
  B10    text-a
  B11    text-b
  B12    text-c
  B13    
  B14
  B15    text-d
  B16 
  B17    text-e
  </code></pre>
  
  <p>In the range B10:B17 I need the formula to return the value 16, which is the last row with no data entered.</p>
  
  <p>I have tried various permutations of INDEX/COUNTBLANK/LOOKUP but no success.  </p>
  
  <p>Any ideas?</p>