When Charles W Jackson Jr's granddaughter handed him the slip of paper from inside her fortune cookie after a family dinner out, neither knew how it would change their lives.

The slip contained a line of "lucky" numbers, and Mr Jackson has been using them whenever he played the lottery in the two years since, reports news.com.au.

Now that strategy has paid off after the retiree from North Carolina in the US won a massive Powerball jackpot prize of US$344.6 million (NZ$517 million).

The 66-year-old claimed his prize earlier this week and told reporters at a subsequent press conference he owed his incredible luck to that one cookie.

Advertisement

"You play to win, but you never really expect to win the whole dang pot," Mr Jackson told North Carolina Education Lottery officials.

According to CNBC, Mr Jackson originally believed he had won a mere US$50,000 (NZ$75,000) after he failed to realise all of his numbers matched those drawn in the game.

But after double-checking, he discovered he "got them all" — although it was only after an online search that he realised just how much money was about to come his way.

He said he then told his wife: "You ain't going to believe this — I got it all."

Mr Jackson, a former military goods store owner, decided to take his winnings as a lump sum rather than in instalments.

However, he will cop a huge tax bill — in the US, there's a standard federal tax charge of 24 per cent, while North Carolina has an extra 5.5 per cent state tax rate.

Once all taxes are paid, Mr Jackson will take home around US$158 million (NZ$237 million), CNBC reports.

Mr Jackson said he planned to continue living a normal life despite the huge prize.

Advertisement

"It probably won't change much … I mean, let me put it this way, I will still wear jeans. But I will probably buy some new ones," he said.

Apart from a new pair of jeans, Mr Jackson will donate some cash to charities and organisations, including St Jude Children's Research Hospital, Shriners Hospitals for Children and the Wounded Warrior Project.

He and his wife are also planning a holiday to Vietnam, and he will also give his brother US$1 million (NZ$1.5 million) after the siblings promised to give each other that amount if they ever won lotto.

According to local news station WRAL, Mr Jackson has been buying lottery tickets for two decades, although he has only ever won small amounts — until now.

His win has broke state records, and the shop that sold him his lucky ticket will also receive a US$50,000 (NZ$75,000) bonus.