title: What does E9 at the end of casted string to double value means ?
body: <p>I am doing some simple programming task just to keep up and understand some tricky and hidden stuff. 
  Here is this program: </p>
  
  <pre><code>String numbersArray = "1000000001 1000000002 1000000003 1000000004 1000000005";
  String[] stringNumbers = numbersArray.split(" ");
  double sum = 0;
  
  for (String s : stringNumbers) {
  
      try {
  
          double number = Double.valueOf(s);
          sum += number;
  
      } catch (Exception e) {
  
          System.out.println("Unable to cast " + s + " to double!");
  
      }
  
  }
  System.out.println(sum); 
  </code></pre>
  
  <p>When I debug the - put break point on <code>sum+=number;</code>
  the debugger show something like </p>
  
  <pre><code>number = 1.000000001E9 
  </code></pre>
  
  <p>and when I print out the result it is </p>
  
  <pre><code>5.000000015E9
  </code></pre>
  
  <p>So what <code>E9</code> mean and why there is a dot <code>"."</code> before the last number ? </p>