title: Tableau - Using Lookup and Grand Total in calculation formula
body: <p>I am new to using Tableau, and I am trying to make a calculation row below grand total.</p>
  
  <p>The row will take will take the count of null values of each month from the grand total. </p>
  
  <p>I presume the best way would be to use the lookup function(Contains "Null").  Or could I use an offset ?</p>
  
  <p>I would appreciate some help with the syntax of the calculation field.</p>
  
  <p><a href="https://i.stack.imgur.com/tNmc8.png" rel="nofollow noreferrer">TableauTable</a></p>
  
  <p><a href="https://i.stack.imgur.com/NNiA3.jpg" rel="nofollow noreferrer">Attempt</a></p>