A CHALLENGING brain teaser is asking people to find the “missing pound” – and it’s left internet users scratching their heads.
A video has been shared on TikTok that has racked up thousands of comments from people who are unable to solve a restaurant dilemma.
The clip starts with a person sat with a pen and paper trying to solve the brain teaser, with the voiceover saying: “Okay someone explain this to me, because I just don’t get it.”
The riddle is that three friends go out for a meal and split the bill at the end, with each contributing £10 to make a combined £30.
The meal total comes to £25 so the waiter has to give them £5 in change.
As he is left confused as to how to split this amount equally, he gives them £1 each back and keeps £2 for himself.
The three pals are given £1 back so they have now only paid £9 each, giving a total of £27, plus the £2 the waiter kept, which comes to £29.
So where has the extra pound gone?
Many people were left baffled, with one saying: “NO. That pound actually disappeared.”
Another said: “The only thing I can think is that when we invented maths we got it wrong.”
And one simply gave up saying: “Too much math for me.”
So how do you solve it? The answer is actually quite simple.
The £1 is actually not missing and the riddle is an example of informal fallacy – and the error lies in the reasoning.
We lose track of the ‘missing’ pound when we conceptualise the riddle because, in reality, the customers have not paid £27 between them – the bill was actually £25, whilst the extra £2 went to the waiter.
Therefore, of the £30 which changed hands, £25 has gone to the restaurant.
This leaves the £2 which the waiter nabbed and then the £3 in refunds split between the three customers – which all adds up to £30.
It all makes much more sense if you do the maths the other way round: £30 = £1 + £1 +£1 + £2 + £25
Next time you’re out to dinner, it might be less of a head-scratching hassle to just let the waiter keep the change.
Want another challenge?
And can you name these ’90s chocolate bars? Take this tasty quiz to find out.