You can buy a "Mobilis Pass" instead of carnets.
This is a good option for those who find using one ticket more convenient.
It can be difficult to tell used carnet tickets from unvalidated tickets.
The tickets in carnets are used for one-way trips, while the Mobilis Pass is an all day pass which is good for unlimited travel on Metro or Bus.
The only restriction on Mobilis Pass is that travel must be completed by midnight of the same day you begin using it and you must write your name and the date on the pass before using it.
You must also validate the pass each time you use Metro or Bus.
You can purchase the Mobilis Pass in the machines in Metro stations. You will only need Zone 1-2 if staying in Paris, and this pass costs 7.30 EU per day. Here's the information:
Terms of use:
With Mobilis, you can have unlimited travel in selected areas .
You can move on all modes of transport in Île-de-France, Metro, RER Bus, Tram and train except Filéo and links to airports (Orlyval, Orlybus, Roissybus, Orly and Roissy by RER ).
Access by lines 183 and 285 to Orly airport and the lines 350 and 351 for Roissy airport is possible (for the areas concerned).
For all packages (regardless of duration), the validity period starts at the first available service and ends at midnight.
Mobilis is in the form of a magnetic ticket corresponding to the selected areas. Before use, you must register on the coupon your name, first name and date of use. Validate the ticket each time you use transport.