In his latest investor letter, Warren Buffett revealed an important clue regarding what's in store for Berkshire Hathaway's (NYSE: BRK-B) (NYSE: BRK-A) largest holding, Coca-Cola (NYSE: KO).

"In 2011," he wrote, "we [Berkshire Hathaway] will almost certainly receive $376 million from Coke, up $24 million from last year. Within 10 years, I would expect that $376 million to double."

Say what, Buffett? You expect Coke's dividend to double in a decade's time? My math reveals that Coke would have to grow its dividend by at least 7% per year for that to happen. This is interesting, since Wall Street rarely expects a 7%-plus growth rate from a mature consumer staple like Coke.

But Buffett's caffeinated bullishness didn't stop there -- not by a long shot: "By the end of that period, I wouldn't be surprised to see our share of Coke's annual earnings exceed 100% of what we paid for the investment. Time is the friend of the wonderful business."

Since Berkshire Hathaway has paid a total of $1.3 billion to acquire its 8.6% stake in Coke over the years, that implies that Buffett thinks Coke could be generating $15 billion in earnings in 10 years! (I'm a free cash flow guy myself, as is Buffett, but Coke's stated earnings generally equal its free cash flow.)

At first glance, saying Coke will make $15 billion in a decade may not be such a newsworthy event. After all, Coke made $11.8 billion in 2010. But fiscal 2010's result is an anomaly, arising from a one-time non-cash gain related to its acquisition of the North American operations of Coca-Cola Enterprises (NYSE: CCE). Also, consider that Buffett brought up that number in the context of Coke's greatness as a company. I doubt he'd do so if it he didn't think it significant.

Using Coke's $8.449 billion in operating income as the starting point -- and we know how much Buffett likes operating income -- the Oracle's $15 billion projection gives us a 5.9% growth rate for Coke. That's similar to Buffett's 7% growth rate projection, which accounts for dividends.

Why 7% matters
So why get all hot and bothered about a 5.9%-7% growth rate? For starters, 7% compounded is more than adequate to make Coca-Cola a special investment. If Coca-Cola doubles its earning power in the next 10 years as Buffett predicts, then Coke could stop growing in 2021 and still be priced to deliver to returns in the 8%-8.5% range, according to a discounted cash flow model.

And since 8%-8.5% is greater than 7%, if Buffett is right, you'll more than double your money in 10 years, and quadruple it in 20. And all this for investing in an industry leader that isn't saddled with PepsiCo's (NYSE: PEP) lower-margin snack business, and has greater international scale than Dr. Pepper Snapple (NYSE: DPS). Coke turns every $1.00 of sales into $0.24 of operating income, while the competition lingers at $0.14 and $0.18, respectively.

Maybe this is what Buffett meant when he said, "Time is the friend of a wonderful business."

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Fool contributor Chris Baines wishes he could buy the world a Coke. Chris owns shares of Berkshire Hathaway. He actively participates in CAPS as cbaines2. Berkshire Hathaway is a Motley Fool Stock Advisor choice. Coca-Cola and PepsiCo are Motley Fool Income Investor recommendations. The Fool owns shares of Berkshire Hathaway. Try any of our Foolish newsletter services free for 30 days. The Fool has a disclosure policy.