codice:
	var a = 10;
	var b = 20;
	var c = null;
	var d = null;
	
	c = a.toString() + b.toString();
	alert(c);
	
	d = a + b;
	alert(d);
	
	c = "" + a + b;
	alert(c);
	
	d = a + b - 0;
	alert(d);