title: SAS: How do I point to a specific observation of a value?
body: <p>I'm very new to SAS and I'm trying to figure out some basic things available in other languages.</p>
  
  <p>I have a table</p>
  
  <pre><code>ID  Number
  --  ------
  1   2
  2   5
  3   6
  4   1
  </code></pre>
  
  <p>I would like to create a new variable where I sum the value of one observation of Number to each other observations, like</p>
  
  <pre><code>Number2 = Number + Number[3]
  
  ID  Number  Number2
  --  ------  ------
  1   2       8
  2   5       11
  3   6       12
  4   1       7
  </code></pre>
  
  <p>How to I get the value of third observation of Number and add this to each observation of <code>Number</code> in a new variable?</p>