title: SUMIF to sum cells only if other corresponding cells contain a number
body: <p>I'm trying to solve this:</p>
  
  <p><a href="https://i.stack.imgur.com/csz6Y.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/csz6Y.jpg" alt="enter image description here"></a></p>
  
  <p>I'm playing around with the <code>sumif</code> and <code>sumifs</code> function but I can't seem to figure it out.</p>
  
  <p>It's important to sum up all cells of B only, and only if the corresponding cells A have a number in it (any number will do). This condition is important, because some cells are empty, some have random strings in it, some are marked with "N.A.", etc.</p>