The 'must win' Lotto jackpot on Saturday is much more likely to be shared, according to a mathematician.
Eamonn Toland was speaking after the National Lottery said the record-breaking €19.06m jackpot will be won on January 15th.
It follows criticism after the jackpot has rolled over since June 2021.
While a National Lottery spokesperson says if the jackpot is not won outright, it will be split.
And new rules to future draws mean jackpots will have to be won "no more than five draws after the cap has been reached".
Mr Toland told The Hard Shoulder the normal odds of winning are 11 million to one.
"The odds of somebody winning the lotto in the normal course of events are about 11 million to one.
"That's to win the jackpot by matching six."
He says the odds of winning a 'must-win' jackpot depends heavily on ticket sales.
"I suppose the odds of winning the jackpot - whether by a match six or matching five-plus or matching five - it's a very wide estimate because we don't have access to the raw data.
"But we would put it at somewhere between 250,000 to one, and 500,000 to one".
'Not great odds'
But he says sharing the jackpot is very likely.
"They're better odds, they're still not great odds - and I suppose the kicker is that in this new scenario, you're much more likely to end up sharing the prize with other people.
"For example, if it goes down to the match five you're going to have maybe 40 or 50 other people sharing that pot with you.
"And I suppose a little bit ironically, you could win the jackpot and still not end up getting the million".
He says under the old rules, the jackpot was won around one in every seven draws.
"Under the old system, I suppose the odds of a rollover seem to be somewhere around one in every seven draws roughly the jackpot was won... which means six out of seven times the jackpot wasn't won and there was a rollover.
"So I suppose it was six times, roughly, more likely to rollover than not to rollover."
And he says this type of rollover will never happen again.
"We're never going to see this situation of 62 rollovers in a row, which was something that was extremely unusual and extremely unlikely - but it did happen.
"But that can never happen again in the future".