function soNumero(e){
	if(window.event) {
		key = e.keyCode;
	}else if(e.which){
		key = e.which;
	}
	if (key!=8 || key < 48 || key > 57) return (((key > 47) && (key < 58)) || (key==8));
	{
    	return true;
  	}
}