London, UK, the venue for this International Mathematical Olympiad Competition.

In the past few days, the Olympic Mathematical Olympiad competition teams from more than 100 countries around the world have arrived in London one after another.

Greenwich time has an eight-hour time difference from the time in the capital of China. The Chinese Mathematical Olympics national team arrived in London three days in advance, leaving time for counter-difference.

The British organizer arranged for the Chinese Mathematical Olympic team to stay in a hotel near Waterloo Station, which is not far from the University of South Bank of London and can be reached within a ten-minute walk.

The team leader, deputy team leader, coach, translator, logistics officer and six team members of the China Mathematical Olympics team were all satisfied with the accommodation arrangement. The hotel was not luxurious but clean and comfortable, and was also very close to the IMO competition venue of London South Bank University.

Shen Qi and Zhou Yuan lived in a room, and they both persisted until the end and were selected into the official list of six players in the Chinese Mathematical Olympiad competition team.

Two young men of the same age are full of energy. This is their first time to come to the UK. They don’t want to get the jet lag. They put their luggage in the hotel, and Shen Qi and Zhou Yuan went out to play together.

Of course, they didn't dare to walk too far. They just walked around the hotel, with an activity radius of no more than 3 miles.

As soon as he left the hotel gate, Shen Qi discovered something that shocked him.

"Hey, Zhou Yuan, look here. My English level is average, but I know all the English on this brand. If I read it correctly, they can't sell even a box of strawberries." Shen Qi stopped in front of a supermarket on Waterloo Street.

There is a sign standing at the door of this Tesco supermarket, which reads in English: "Today's special offer, 1 lb/box of strawberries, 3 lb/two boxes."

Zhou Yuan's English is good. He quickly understood the discount information and thought about it and said: "Maybe the British used a mysterious and special number system, with 1 directly following 3, and there is no 2."

"Haha, Zhou Yuan, you have poked my laughter. I would rather believe that this is a typo. Let's go into the supermarket and take a look." Shen Qi pulled Zhou Yuan into the supermarket together.

After walking in the supermarket for a few minutes, Shen Qi keenly discovered that "1 lb/box of strawberries, 3 lb/two boxes" was not like the mistake of the supermarket promotion manager.

There is a shelf with chocolate products, among which Hershey Chocolate is being promoted. The supermarket’s promotional information is: “HEYSHEY’S-30%-off,?18.5.”

"Hey, Zhou Yuan, look at it. The original price of Hershey chocolate is 15 pounds per box, and 30% off means 30% off, so the discount price should be 10.5 pounds per box, and what the hell is this 18.5 pounds?" Shen Qi fell into deep thought.

After thinking, Zhou Yu'anluo said, "This store wants to close and refuse customers outside the door?"

Looking at the endless stream of local customers, Shen Qi shook his head: "However, this is not the case. Look, this supermarket has a large flow of customers and can be said to be prosperous. I am also surprised that there are actually customers who buy strawberries and Hershey, and there are still quite a few!"

Zhou Yuan carefully observed a cashier not far away, and the promotional strawberries of "1 lb/box, 3 lb/two boxes". A British sister bought 8 boxes in one go. She was very happy, as if she had taken a big advantage.

After the British elder sister bought the order, a blond guy put 4 boxes of Hershey chocolate on the cashier, laughing and the sun shining brightly.

Shen Qi and Zhou Yuan looked at each other, speechless.

"I'm afraid... the residents of this area are all fools?" Shen Qi derived this hypothesis.

"It's obvious that this is a black store, and the customers are all fools." Zhou Yuan nodded, agreeing with Shen Qi's assumption.

"London, the capital of finance, the capital of fashion, the capital of football, the capital of fools?" Shen Qi further deduced the second hypothesis.

"It is also possible that the people of London are generally rich. After all, they are the capital of the Empire that the sun never sets. It is understandable that people are stupid and have more money." Zhou Yuan added a new supplementary assumption based on Shen Qi.

"Olympic mathematics competition, Olympic Games in mathematics, intellectual competitions for high IQ people, Zhou Yuan, why should we arrange to be held in the Capital of Fools?"

"Maybe it is to highlight...contrast cuteness?"

The two Chinese young men walked among a group of white, black and Indians, feeling that the world was so amazing that they had a long experience.

"Zhou Yuan, you're here, you can't go back empty-handed, just buy something, after all, it's produced in the UK." Shen Qi took a shopping basket, stopped and took some snacks on the shelves.

Zhou Yuan was quite frugal, so he bought a toothpaste and held it directly in his hand: "When I entered the customs, my Chinese toothpaste was confiscated by the British as a dangerous biochemical product. I have to buy a toothpaste for a few days."

"Give me the toothpaste, I'll pay the bill together." Shen Qi took the toothpaste from Zhou Yu'an's hand and put it into his own basket.

Sitting in line at the cashier, Shen Qi and Zhou Yuan were waiting to pay.

A few minutes later, the two came to the cashier, and Shen Qi put his shopping basket on the cashier.

"Hello." said the cashier girl in English, a young red-haired white girl.

"Yes." Shen Qi nodded and said nothing.

The cashier took out items from the shopping basket in a sloppy manner, scanned the code, and the total amount was displayed on the cashier computer: 33.50 pounds.

"33 pounds and 50 pence." The cashier said to Shen Qi.

"Water?" Shen Qi was puzzled.

"33 pounds...50 pence." The cashier repeated it and his speech slowed down.

Shen Qi said to Zhou Yuan: "I bought a box of biscuits for 5.8 pounds, a muffin for 4.6 pounds, three donuts for 5.4 pounds, and five packs of potato chips. The unit price for each pack of potato chips is 2 pounds, and you can enjoy a 20% discount on five packs. With Zhou Yuan's toothpaste for 2.2 pounds, and the 7% consumption tax here, I should pay 27.82 pounds for our consumption, not 33.50 pounds. No matter how you calculate it, you can't calculate the result of 33.50."

"That's right, it's 27 pounds and 82 pence." Zhou Yuan also calculated the total amount in a very short time.

"Hey, young gentlemen, do you need these goods?" The cashier girl saw that Shen Qi and Zhou Yuan had been talking for a long time, but she couldn't understand Chinese, so she reminded her, keeping her patient enough.

"Sorry." Shen Qi said apologetically to the cashier's girl, and then said to Zhou Yuan: "You speak English more than 6. Tell the consumption details I just mentioned to this red-haired lady and translate them into English."

"OK." Zhou Yu'an nodded and said in English to the cashier girl: "Ms., I think you have calculated the amount of our consumption incorrectly."

The cashier shook his head firmly: "Impossible, this is the result of computer calculations."

Zhou Yuan reported the details in one go. His English spoken language was very fluent: "A box of cookies 5.8 pounds, a muffin 4.6 pounds, three donuts 5.4 pounds, a toothpaste 2.2 pounds, five packs of potato chips enjoy a 20% discount of 8 pounds. Including the 7% consumption tax, we need to pay a total of 27 pounds and 82 pence, which we think is a reasonable and correct amount."

The cashier girl was stunned for a moment: "You...what were you talking about?"
Chapter completed!