function IsNumeric(sText)
{
   var ValidChars = "0123456789";
   var IsNumber = true;
   var Char;

   for (i = 0; i < sText.length && IsNumber == true; i++)
   {
      Char = sText.charAt(i);
      if (ValidChars.indexOf(Char) == -1)
      {
         IsNumber = false;
      }
   }
   return IsNumber;
}