// onkeydown="return isnum(event,false,false,this);"

function isnum(x, allowDecimal, allowNegative, obj)
{
  if (x.keyCode == 9)
    return true;

  if (allowDecimal == true && (x.keyCode == 190 || x.keyCode == 110))
  {
    if (obj.value.indexOf('.') == -1)
      return true;
    else
      return false;
  };
  
  if (allowNegative == true && (x.keyCode == 189 || x.keyCode == 109))
  {
    if (obj.value.indexOf('-') == -1)
    {
      obj.value = "-" + obj.value;
      return false;
    }
    else
      return false;
  };
  
  if (x.keyCode<48 || x.keyCode>57)
  {
    if (x.keyCode!=8 && x.keyCode!= 46 && x.keyCode!=37 && x.keyCode!=38 && x.keyCode!=39 && x.keyCode!=40 && x.keyCode!=36 && x.keyCode!=35)
    {
      if (x.keyCode<96 || x.keyCode>105)
        return false;
    };
  };
  
  if (x.keyCode>47 && x.keyCode<58 && x.shiftKey == true)
    return false;

  return true;
};