I divided $60,000,000 by $29.99 and came up with a little over two million. I figured half went to the retailer so that’s four million. Others can check my math.
Another way to look at potential domestic sales: 66 million people voted for Obama in 2012. If 5% of Obama voters bought the book at $20 per copy, that’s 3,300,000 people spending $66,000,000. Some of them will be high school and college students who have to buy it for a class, libraries, university departments, etc.