Number of 'entries' required to visit China/Hong Kong/Macau

My wife and I will be travelling to China in October 2015 as tourists on an 8 night tour. We have also booked a 4 night stay in Hong Kong on our return trip back to Australia. We would also like to visit Macau while in Hong Kong. How many 'entries' will I have to apply for or will the single 'entry' be enough ? Thank you.