@Multiple or single entry visa

A am an Australian citizen. I am going to China with a group tour for 1 week and then staying back for 10 days with my brother who works in Changshu. After that I will go to Norway (from Shanghai) for 20 days and returtn to shnghai for a day before returning back to Sydney.
Do I need a multiple entry or I don't need one for my second entry which is for less than 72 hours?