A $4 million jackpot in the Philippines ended up with 433 winners. Officials are calling for an inquiry.

• In the Philippines, 433 people won a $4 million lottery jackpot.
• Officials are calling for a probe into the draw, as all the winning numbers are multiples of nine.

Government officials in the Philippines are calling for a probe into a Grand Lotto outcome that saw hundreds of people win a jackpot worth 236 million peso, or around $4 million.

Participants in the Grand Lotto select six numbers ranging from one to 55, and all six numbers have to match those drawn by the lottery operator, the BBC reported.

The Philippine Charity Sweepstakes Office, the lottery organizers, announced that 433 people had won the lottery held on October 1. Each of the winners is set to win nearly $10,000.

That's the highest number of people to have ever won the Philippines' Grand Lotto top prize, the BBC reported, citing local media.

The kicker? All winning numbers were multiples of nine: nine, 18, 27, 36, 45, and 54, Bloomberg reported.

"I've always been betting on the pattern 9, pattern 8, pattern 7 and pattern 6 for many years, and I am thankful that this time, I won," one unnamed winner who was interviewed by the lottery agency said, per the Star.

But Terence Tao, a math professor from the University of California, Los Angeles, told the BBC that this pattern of winning numbers is rare "for any single lottery."

The outcome also drew skepticism from government officials. Aquilino Pimentel III, the Philippines' senate minority leader, asked for a probe into the draw and described the event as "strange and unusual" to Bloomberg.

"These lotto games are authorized by the Republic of the Philippines. Therefore, we need to maintain and protect the integrity of these gambling games," he told Bloomberg.

Lottery officials were quick to defend the results. Melquiades Robles, the general manager of the sweepstakes office, told Bloomberg there was nothing irregular with the results. People tend to cling to their chosen numbers and bet on the same combinations over and over, he added.

In a Facebook post congratulating the winners on October 3, Robles wrote: "Lottery is a game of chance, nothing is definite and it is uncontrollable. To the 433 new jackpot winners, it pays to be loyal."

The Philippine Charity Sweepstakes Office declined Insider's request for comment.

The news also caused a stir on social media. One person took to Twitter to comment on the odds: "1 bettor has a 1-in-40 million chance of winning. 433 bettors just beat those odds."

Others weighed in with disbelief. An op-ed columnist at the Phil Biz News tweeted on the matter, saying: "What a joke—just like the jokes running the organization."

"Was it just CHANCE or INTENTIONAL?" questioned one person in a series of tweets on October 4.