title: NumberFormatter issue for large number
body: <p>I try this code for converting string to number and vic versa.
  this code must print the same outputs. but its output is not correct.
  can any one help me?</p>
  
  <pre><code>let formatter: NumberFormatter = NumberFormatter()
  formatter.locale = Locale(identifier: "en_US")
  
  
  if let r1 = formatter.number(from: "10123456789012349") , let r2 = formatter.string(from:r1){
  
       print(r1) // output = 10123456789012349
       print(r2) // output = 10123456789012348
  }
  </code></pre>
  
  <p>also this code has same problem</p>
  
  <pre><code>print(formatter.string(from:NSNumber(value: 10123456789012349)))
  //output is 10123456789012348
  </code></pre>