title: Leave a cell blank if condition is false
body: <p>Other questions have touched on this and offered solutions that are not viable for a very large data set. I have a formula like the following across 9 columns:</p>
  
  <pre><code>=IF(A1=A2, B2, "zz") 
  </code></pre>
  
  <p>I then autofill about 3.5 million cells + copy -> paste values. Then I find and replace "zz" with "empty cell". However, finding and replacing a million or so "zz" strings is a very slow process. I'd rather not write anything there in the first place. So my question is, how to I write the following formula:</p>
  
  <pre><code>=IF(A1=A2, B2, 'leave cell alone and write nothing there at all')
  </code></pre>
  
  <p>Excel seems to be incapable of not touching a cell in case of FALSE (or TRUE for that matter).</p>