Sometimes you have to make your own luck.

An elderly couple stands to make millions of dollars after purchasing more than $600,000 worth of lottery tickets over a three-day period, according to a report by the Boston Globe.

Marjorie and Gerald Selbee, both in their 70s, each bought $307,000 worth of $2 tickets for a relatively obscure Massachusetts lottery called Cash WinFall. One location that sold them half the tickets, Billy’s Beer and Wine, had sold only $47 worth of lottery tickets the day before.

The Selbees are among a small group of gamblers -- including statisticians and engineers from MIT and Northwestern University -- who were able to exploit a lottery loophole providing them with risk-free winnings. The Selbees have already claimed nearly $1 million in prize money this year.

And that’s just the tip of the iceberg, according to Mohan Srivastava, an MIT-educated statistician who gained fame when he found a flaw in a Canadian scratch ticket game that allowed him to pick the winners more than 90 percent of the time

“Cash WinFall isn’t being played as a game of chance. Some smart people have figured out how to get rich while everyone else funds their winnings,” Srivastava told the Boston Globe.

According to Srivastava, because of the way Cash WinFall is setup, a gambler who bought 200,000 tickets during a special four-week period would not only cover his investment, but also make anywhere from $240,000 to $1.4 million in guaranteed profit. All in all, Srivastava calculates the top five groups and individuals playing Cash WinFall collectively win $1 million to $6 million in profits every year from less than two weeks of gambling, the Globe reported.

How it Works

The secret is timing.

The game itself is simple: If the numbers on six randomly selected balls match the ones on your ticket, you win the jackpot -- which only one person has ever won since the game’s creation in 2004.

The jackpot grows slowly over time from a low of $500,000 to a limit of $2 million to $2.5 million. When the limit is reached and no one has won, the jackpot is redistributed across the smaller prizes for those who matched three, four or five numbers correctly.

See Also: Statistician Cracks Secret Code Behind Lottery Tickets

When these "rolldowns" occur, the odds of a significant payout increase dramatically.

According to Mark Kon, a professor of math and statistics at Boston University, the trick only works if you buy enough tickets. Someone who buys $100,000 worth of tickets has a 74 percent chance of winning during the rolldown week; for bettors like Selbee who spend at least $500,000, there is nearly no risk of losing money, Kon told the Boston Globe.

But Paul Sternburg, the lottery’s executive director, believes they have no reason to apologize or even change the lottery's procedures -- pointing to $11.8 million in profits in 2011.

"It’s a niche game for a different audience," he told the Boston Globe. "You want to bring in as many players as possible. Some people chase a huge jackpot. Others are looking at odds."

For more savvy players -- including an engineer from MIT -- who have bested the lottery, see the full story on The Boston Globe.