title: compute sum dynamically with javascript
body: <p>I have two textboxes <code>Num1</code> and <code>Num2</code> and another textbox <code>Sum</code> having the value <code>10</code>.</p>
  
  <p>How can I do this wherein if the user will enter a number for <code>Num1</code>, it will add it to <code>Sum</code> and dynamically change the displayed number in the <code>Sum</code> textbox. If the user will enter a number in <code>Num2</code> it will also add that number to the updated number shown in <code>Sum</code> textbox and dynamically change the value for <code>Sum</code> textbox also.</p>
  
  <p>How to do this in Javascript?</p>