Lotto Powerball $50 million: What you need to know about the must-be-won draw

More than two million tickets are expected to be snapped up by Lotto players ahead of tonight's astronomical $50 million Powerball draw.

If a single ticket-holder won, the prize would be the largest in New Zealand history, edging out a Hibiscus Coast couple who won $44m in 2016.

A bog-standard draw with a lower Powerball figure would typically only reach about 500,000 ticket sales - 1.7 million were sold for Wednesday's $44m draw.

A must-be-won draw was called on Wednesday after the jackpot swelled to $50m, the cap-limit Powerball can reach in New Zealand.

Simply put, the draw must be won. If there were no First Division winners, the entire jackpot would roll down to the next division where there were winners.

If there was more than one winner in a division, the total prize would be shared evenly among all of the winners.

A number of procedures have to be followed before the draw can be made. Photo / Supplied

In October, two separate Lotto winners from Auckland split a Powerball jackpot of $38m, each taking home $19.1m.

Two years ago, a record 40 individual ticket holders shared a First Division prize worth $1m.

People without Lotto tickets already were advised to get in early, head of communications and corporate social responsibility Marie Winfield said.

"Whether it's one lucky winner or more, we're so excited that we'll be making more New Zealanders millionaires this week," Winfield said.

"Everyone around the country is dreaming about how they would spend $50, and with it being a must-be-won draw, the massive prize has to go."

If players haven't bought a ticket, it might be worth buying a dip instead of picking your own numbers.

Of the previous big Lotto winners, 73 per cent won with a dip ticket - not by selecting their own numbers.

The most commonly selected Lotto numbers, in order of frequency, over the past 32-odd years Lotto had been running were 1, 7, 22, 19, 13 and 18.

Meanwhile, the least commonly drawn numbers (worst first) were 28, 29, 34, 4, 3 and 11.

Powerball's $50m draw must be won. Photo / Supplied

The most frequently drawn Powerball number, meanwhile, was the number 2, followed by 6, 3, 1, 5, 4, 8, 7, 10, 9.

But the hardworking staff at Lotto don't just rock up and do the draw, there are procedures and controls in place to run through first.

At least three people had to be present to make sure everything was up to scratch, two Lotto NZ representatives and one Audit NZ scrutineer.

Locked in a secure storage unit were four sets of balls, two each for Lotto and Powerball, as well as the draw machines which also had two each.

Two keys were required to unlock the unit, with security guards having to hand them over to one Lotto rep and the scrutineer.

The seals would be checked to confirm there had been no changes since it was closed.

To see which machine and ball sets would be used, one of two old 20c coins were tossed.

Once in the studio, each machine was run through a robust full draw cycle a minimum of four times before the actual draw.

In the rare instance of an issue with a machine arising during testing, it would be replaced for the other machine.

It was a similar story in regard to the balls, if one fell to the ground the entire set would be taken out and swapped for the other.

At the completion of the draw, the Audit NZ scrutineer checked and confirmed the results had been correctly recorded on the Official Results Certificate.