Robert Winburn of Urbandale, Iowa, has been playing the same Powerball lottery numbers over and over for 20 years, and they've finally paid off.

The 49-year-old man may not have won the $330.8 Powerball jackpot on Saturday, but he came close, matching five numbers and earning himself a $1 million prize.

According to a press release from the Iowa Lottery, Winburn didn't realize his good luck until the following day when he scanned his tickets using a self-checker at a grocery store.

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"I put the first three (tickets) in and no win," Winburn told lottery employees Tuesday as he claimed his prize at the lottery's headquarters in Des Moines. "Then (the winning) one came up. I just kind of glanced at it."

He scanned the ticket again to double-check.

"I did tell the guy next to me, 'I don't believe this,'" he said. "And he leaned over and I did it again and he says, 'Sign it and get the heck out of here.'"

He chose not to do a public press conference, but said his number-picking strategy involved assigning letters to the numbers of the alphabet and playing the numbers that corresponded to the letters in his last name.

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Winburn already has plans for his winnings. He's going to buy a newer car, pay bills and invest the rest.

His number-playing strategy had previously won him $100.

Winburn bought his lucky ticket - one of nine $1 million Powerball winners across the country - at Git-N-Go in Urbandale. The store will get a $1,000 bonus from the lottery.

Another ticket in Texas earned its buyer a $2 million prize because the ticket-holder added the Power Play option to the purchase, automatically multiplying the prize.

The Powerball jackpot has swelled to $400 million - the sixth-largest jackpot in U.S. lottery history. Numbers will be drawn Wednesday night.

Courtesy The Iowa Lottery