title: How to check if VBA formula is correct
body: <p>I'm creating a VB macro that converts string values like "1+1" to formulas.</p>
  
  <pre><code>   Cells(1, 1).Formula = "=" &amp; Cells(1, 1).Value
  </code></pre>
  
  <p>But if Value string can't be calculated i have Run-time Error '1004'.</p>
  
  <p>How can i be sure that string would convert to formula successfully?</p>