title: Excel VBA if formula value in cell is less than zero then msgbox
body: <p>Im trying to get a msgbox when the value in the cell which is updated with a formula is less than zero.</p>
  
  <p>For example:</p>
  
  <p>a1= 5</p>
  
  <p>b5= a1</p>
  
  <p>if b5 is less than zero then msgbox "your value is less than zero"</p>
  
  <p>Hope someone can help me</p>
  
  <p>Thank you!</p>