title: Regarding java.math.BigInteger
body: <p>The problem im facing with BigInteger when i try computing a string like "7+3" and then storing the result in a BigInteger variable, it throws a NumberFormat exception. Any pointers on how this can worked on?
  Eg:</p>
  
  <pre><code>    String ist="7+2";
      java.math.BigInteger a = new java.math.BigInteger(ist);
  </code></pre>