function isNumberKey(evt)
      {
         var charCode = (evt.which) ? evt.which : event.keyCode
         if (charCode > 31 && (charCode < 48 || charCode > 57))
            return false;

         return true;
      }
function tax()
{
var pay = document.form1.pay.value;
var g = document.form1.g.selectedIndex;
var a = document.form1.a.selectedIndex;
if(pay <= 150000)
{
document.form1.t.value="nil";
}
else if((a==0) && (g==1) && (pay<=180000))
{
document.form1.t.value="nil";
}
else if((a==0) && (g==0) && ((pay>=150009) || (pay<=300000)))
{
document.form1.t.value=((10/100)*(pay-150000));
}
else if((a==0) && (g==0) && ((pay>=300010) || (pay<=500000)))
{
document.form1.t.value=((15000+(20/100))*(pay-300000));
}
else if((a==0) && (g==0) && (pay>=500001))
{
document.form1.t.value=((55000+(30/100)*(pay-500000)));
}
else if((a==0) && (g==1) && ((pay>=180010) || (pay<=300000)))
{
document.form1.t.value=((10/100)*(pay-180000));
}
else if((a==0) && (g==1) && ((pay>=300010) || (pay<=500000)))
{
document.form1.t.value=((12000+(20/100)*(pay-300000)));

}
else if((a==0) && (g==1) && (pay>=500001))
{
document.form1.t.value=((52000+(330/100)*(pay-500000)));
}
else if((a==1) && (pay<=225000))
{
document.form1.t.value="nil";
}
else if((a==1) && ((pay>=225010) || (pay<=300000)))
{
document.form1.t.value=((10/100)*(pay-225000));
}
else if((a==1) && ((pay>=300010) || (pay<=500000)))
{
document.form1.t.value=((7500+(20/100)*(pay-300000)));
}
else if((a==1) && (pay>=5000001))
{
document.form1.t.value=((47500+(30/100)*(pay-500000)));
}
}