title: how do I find the values that are in one column but not in the other
body: <p>I have two columns A and B in a google spreadsheet.</p>
  
  <p>I want to find all the numbers that are in column A but not in B. How do I do that?</p>
  
  <p>B could have the same numbers from column A. </p>
  
  <p>So if column A has numbers: 1, 2, 3
  and B has numbers 3, 4,5</p>
  
  <p>I want to get all the numbers that are in A but not in B:
  1, 2</p>
  
  <p>How do I do that using google spread sheet?</p>