title: How to know or calculate empty or blank cells on google sheets?
body: <p>I have a big list of products on google sheets about 900 rows.
  And on these rows is the information about every product, when customers buy one I put the id of the product in ID product column.</p>
  
  <p>Now I want to now how many cells are blank or empty I can't Calculate manually every 900 cells.</p>
  
  <p>How can I create a function that helps me calculate empty cells on your list on google sheets?</p>