I also agree with Warmsnickers. With a Carte Orange, as opposed to a carnet, you can do things like forget something at your hotel, remember it after you have passed the turnstile, go back and get it and not have wasted a ticket. Also, if the weather turns mean, and you're only one Metro stop from where you are headed, you take the ride for that one stop...again not wasting a ticket. I used the equivalent of a carnet in two days. If you plan to use the metro as a "magic carpet" and IF your plans coincide with the Mon-Sun weekly validity, it's a great deal and a better one than the carnet.