Flying Ryanair doesn't always add up - and now there's scientific proof of that, it's been claimed.
Regular flyers will be familiar with the claims from the flight crew that buying two of the airline's scratchcards doubles your odds of winning.
But a passenger, scientist David Robert Grimes, recently did the maths and claims that this couldn't be correct.
Ryanair sells its scratchcards onboard their route network alongside snacks and drinks
David Robert Grimes worked out that the probability of doubling your odds by buying two scratchcards wasn't correct and shared his workings on Twitter
Grimes is a scientist who works at Oxford University and regularly flies with the budget airline
Grimes, who has a PhD in physics, worked out the calculations on a notepad in the air and tweeted his results later, reported The Independent.
He Tweeted: 'Ryanair doing 2 scratchcards for price of 1, claimed it'd double your odds of winning. I spent a good 5 minutes checking & this was only true if your chances of winning are always 0 or you bought 0 cards. This is a fine hill to die on, damn it!'
He wrote on the calculations 'no dice O'Leary', referring to Michael O'Leary, Ryanair's chief executive.
The scientist, who normally works on scientific research into cancer modelling at Oxford University, was flying from Dublin to Brussels Chareloi when he figured out the fib.
He told MailOnline Travel: 'The claim is based on a misunderstanding of how probability works - if you flip a coin, your chances of getting a heads is 50 per cent. But it's not 100 per cent if you flip twice. The reality is that we all tend to misunderstand statistics and probability, and they can confound our intuition!'
His discovery hasn't put him off flying with Ryanair, though.
He added: 'I fly Ryanair all the time - and certainly an innocent mistake from an overworked cabin crew member won't change that. It's an entirely understandable error, and I was just having some fun with math pedantry to amuse myself.'
Ryanair told The Independent: 'All of our 129million customers are already a winner thanks to our unbeatable low fares and our scratchcard game offers great prizes including cash, luxury cars and the chance to win €1million, while supporting charities across the UK and Europe. We also offer a bundle of seven cards for the price of five!'
The sale of onboard scratchcards on the Irish budget airline was one of the issues raised by cabin crew recently.
They allege that they are threatened with poor shift patterns if they fail to sell items including scratchcards, food, drink and perfume.
According to The Guardian, documents reveal how much money each crew member is making and asking them to give an explanation when they fail to meet a target.
If their sales fall below the strict targets, crew members are allegedly hit with unfavourable shift patterns and disciplinary measures.
The budget airline raked in £1.6billion last year from more than 16 different 'extras' including baggage charges, leg room and even oxygen as well as in-flight sales.
A Ryanair spokesman said: 'These claims are false. We do monitor and manage sales performance and any crew members that consistently and markedly under-perform are given time and training to improve.'