Question: How many copies did back in black sell?
Answer: an estimated 50 million
Disambiguated annotations:
qaPairs: question: About how many copies did back in black sell worldwide?
answer: 50 million copies
50 million
question: By 13 December 2007, about how many certified copies did back in black sell in the US?
answer: 22 million
22× multi-platinum
22 million American sales
question: About how many certified copies did back in black sell in AC/DC's native Australia?
answer: 180,000
3× Platinum
question: About how many certified copies did back in black sell in the UK?
answer: 600,000