She had to take a second look when handed her receipt, which appeared to show she had a remaining balance of more than £63quadrillion.

A spokesman for the coffee shop said due to an “administrative error”, the gift card number – rather than gift card value – had been entered into the wrong part of the till.

Ms Downing said seeing the seventeen-figure balance – which is more than 2,000 times the size of the United States’ gross domestic product – was “hilarious”, and that the look on the staff’s faces was one of confusion as they handed her the receipt.

The figure was so large the paper didn’t have enough space to contain the number.

She told the BBC: “You don’t ever see anything like that happening. I sent it to my partner and he thought it was really funny as well.”

“I’m just enjoying being the richest woman in the world on paper while it lasts,” she added.

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SOPHIE DOWNING

As a business owner, Ms Downing said she was “never going to take advantage” of having such a large amount of money, and that she just treated herself to another drink with the remainder of her £10 gift card.

A spokesman for 200 Degrees told the BBC: “Due to a technical administrative error, the gift card number, rather than the gift card value was entered into the wrong part of the till.

“As a result, the customer was generated a receipt which suggested they had a rather higher amount of money left on their gift card than they actually did.

“The customer was only charged exactly what they should have been, and after they had completed their purchase, their gift card had exactly the right amount left on it, they just had a receipt which showed a very different amount, which the barista gave them as a souvenir.

“They were then given a correct receipt which showed the true value of the gift card.”

Ms Downing said she would have preferred to have a £63 quadrillion gift card to spend at the supermarket.

As the richest woman in the world for a short while, Ms Downing had about 100,000 times more than Elon Musk, while was also briefly worth 22,500 times more than the UK economy.

The fact she now possessed wealth worth about 670 times more than the global economy was a bit of a clue that something had gone wrong.

She said: “This massive number came up on the till. He said ‘I’ve never seen it before but it’s fine for you to keep it.’ I didn’t clock it until he gave me the receipt. I thought ‘surely not, that’s actually crazy.”.

That money could only be spent at the coffee shop, and when she used the gift card to buy something else she realised the balance had barely been dented and she had several quadrillion quid to spend in the café.

Being a responsible citizen, she didn’t use her powers again, and would probably have been rumbled at some point, with the cafe correcting the error.