title: How to add new observation to already created dataset in SAS?
body: <p>How to add new observation to already created dataset in SAS ? For example, if I have dataset 'dataX' with variable 'x' and 'y' and I want to add new observation which is multiplication by two of the 
  of the observation number n, how can I do it ?</p>
  
  <p>dataX :<br>
  x y<br>
  1 1<br>
  1 21<br>
  2 3   </p>
  
  <p>I want to create :</p>
  
  <p>dataX :<br>
  x y<br>
  1 1<br>
  1 21<br>
  2 3<br>
  10 210</p>
  
  <p>where observation number four is multiplication by ten of observation number two.</p>