title: Check multiple true condition in multiple cells
body: <p>Is there any built-in function to check if there's multiple TRUE condition ? Like
  OR() but can detect if there's more than 1 TRUE. For example : </p>
  
  <p>i use this conditional formatting (custom formula) in cell A3:</p>
  
  <pre><code>=OR(not(isblank(B3)), not(isblank(C3)) , not(isblank(D3)), not(isblank(E3)) )
  </code></pre>
  
  <p>so background color of A3 will become RED if any of those cells (B3,c3,d3,e3) is not blank. But i want it to become RED only if 2 or more cells is not blank. This is to give me warning if there's duplication . I only want 1 cells to be not blank. iF there 2 or more, i want the A3 to be RED so i know there's duplication.</p>