<!--Script by hscripts.com-->
<!--Copywrite of HIOXINDIA-->
<!--More scripts @ http://hscripts.com-->

<script language=javascript>
var a=10; //set the value of first textbox.
var b=20; //set the value of second textbox.
var c=30; //set the value of third textbox.
function app()
{
   if(frm.chk1.checked==true)
      frm.txt.value=a;
  else
     frm.txt.value=0;
  if(frm.chk2.checked==true)
     frm.txt1.value=b;
  else
    frm.txt1.value=0;
  if(frm.chk3.checked==true)
    frm.txt2.value=c;
  else
    frm.txt2.value=0;
   var sum;
  if(frm.chk1.checked || frm.chk2.checked || frm.chk3.checked==true)
  {
    x=parseInt(frm.txt.value);
    y=parseInt(frm.txt1.value);
    z=parseInt(frm.txt2.value);
    sum=x+y+z;
    frm.txt3.value=sum;
  }
  else
    frm.txt3.value=0;   
}
</script>

<!--Script by hscripts.com-->

<!--Script by hscripts.com-->

<form name="frm">
<table style="border:solid green 1px">
  <tr><td>Value1<input type="text" name="txt"><input type="checkbox" name="chk1" onClick="app()"></td></tr>
  <tr><td>Value2<input type="text" name="txt1"><input type="checkbox" name="chk2" onClick="app()"></td></tr>
  <tr><td>Value3<input type="text" name="txt2"><input type="checkbox" name="chk3" onClick="app()"></td></tr>
  <tr><td>Result<input type="text" name="txt3" READONLY></td></tr>
  <tr><td align=center>&copy<a href="http://www.hscripts.com" style="color:#3D366F;text-decoration:none;cursor:pointer;font-size:13px">hscripts.com</a></td></tr></table>
</form>

<!--Script by hscripts.com-->