It's worth it to buy a day public transportation ticket to get around Milan
Milan's single entry ticket is 1.5euros. It's valid for 90 minutes however it recently changed rules so you can only get 1 entry into the metro with it.
The day ticket costs 4.5 euros, equivalent to 3 tickets. If you will be out and about, it's worth to buy the day tickets which is valid for 24hours.
You can buy day tickets on the ATM app, or at the station on the machine