China's 1.4 billion population can't fill the country's millions of empty homes. Here's 3 things that would.

• China has so many excess homes that some estimate you could house three billion people in them.
• A former top official in China mentioned the jaw-dropping figure at an economic forum on Saturday.
• He said the estimate is extreme, but said even China's 1.4 billion people can't fill all of them.

There could be enough vacant homes in China to house up to 3 billion people, a former top China official said.