title: Average every nth row in Libreoffice calc
body: <p>simple problem, but I cannot figure it out.</p>
  
  <p>I have a simple column (with many values) in a spreadsheet.</p>
  
  <p>How can I calculate the average every 2 rows?</p>
  
  <p><img src="https://i.stack.imgur.com/knYm3.png" alt="enter image description here"></p>
  
  <p>Thanks!</p>