The guy knows tech. (AFP PHOTO/Nicholas KAMMNICHOLAS KAMM/AFP/Getty Images)

One of the details buried in the New York Daily News' look at David Axelrod's upcoming book is that Obama was given the chance to see the iPhone before it was publicly available. "If it were legal," Obama reportedly said, "I would buy a boatload of Apple stock. This thing is going to be really big."

"Buy Apple stock" has been pretty sound advice for the past 15 years or so. But just how much would Obama have made if he'd invested, say, a president's salary on AAPL? (Not that he was the president then, but you get the point.)

To answer that, we need to know the answer to a key question: When did this meeting allegedly take place? The book isn't out yet, but we can make some estimates.

The Daily News says the meeting happened in 2007. The iPhone was announced on Jan. 9 of that year, so it's safe to assume that Obama didn't see it until after that point. It was released on June 29. So that gives us about a six-month window.

On Jan. 9, AAPL closed at $92.57, according to Yahoo Finance. That's $12.52 at the current stock price, taking into account stock splits and other changes since. By June 29, it was at $122.04 -- $16.51. On average, the price over that period was at $99.02, the price it closed at on April 27. So let's just say that this is the day Obama bought his stock.

Obama goes out and invests $400,000 in Apple stock on April 27, 2007, at the buy price of $99.02, $13.40 at current valuation. Here's what the stock price has done since then.

As a result, Obama's $400,000 would now be worth $3.6 million.

But that's not all. Obama would also have received 10 dividend payments on the nearly 30,000 shares of stock he currently owns over that time period. (The number of shares he has has increased due to a stock split. He only bought about 4,000 shares.) Those dividends paid him just over $40,000 since late 2012. It's frosting on his cake, but it counts.

So Obama was right about buying the stock -- but, then, the stock price went up 10-fold between January 2001 and January 2007. It wasn't that tough a call.

Was he right, though, about the iPhone being "really big" (assuming he said any of this, which, who even knows)? In 2011, four years into the iPhone's run, Business Insider graphed the amount of revenue Apple was making per product.

Apple expanded massively, thanks to massive sales of a profitable product. So, yeah.

But Obama couldn't buy that stock, out of insider-trading concerns. And he's apparently never even owned an iPhone, due to the security restrictions that come with his current job.

So his prediction was largely accurate -- and it did him absolutely no good.