The best idlers of the Tang Dynasty

Inugami Mita had solved two problems in a row by Du Rui, and he had no other way to fight back. Seeing Du Rui's playful smile, he couldn't help hiding his face and retreating. The deputy pharmacist Hui Ri was unwilling when he saw this. He lost his face and raised his voice.

"Little boy is rude!" Pharmacist Hui Ri walked in front of Du Rui slowly. Although he was nearly forty years old, his height was almost the same as that of Du Rui who was just ten years old.

Pharmacist Hui Ri said: "Since you speak big words, you have also solved this difficult problem."

Du Rui was fearless, and said with a smile: "Your envoy, please write a question!"

Pharmacist Hui Ri pondered for a moment and said: "A farmer's house had a lot of guests on a certain day. There are many guests but few bowls, so the guests share one rice bowl and one soup bowl. The two bowls are two. One person shares one soup bowl, and three people share one soup bowl. In this way, a total of 220 bowls are shared. Now that the guests have left, the farmer wants to record how many guests came yesterday. But it can’t be counted, please sir Help with the calculations."

All the courtiers in the hall heard this question and couldn't help but frown. At this time, the knowledge of seasons and numbers has not yet been circulated. Such a question, even the important officials in the court, can't figure it out for a while.

At this time, Taizong also looked at Du Rui with a worried face. Although this matter is just a game, it is also related to Datang's face, and there is no room for loss when playing.

After listening to the question, Du Rui closed his eyes and pondered for a while, then smiled slightly and said, "I know how many guests there are. There are 120 guests in total, right?"

Pharmacist Hui Ri was also surprised when he heard the words, and couldn't help blurting out: "Yes, there are 120 guests."

杜睿意味深长地盯了药师惠日一眼不慌不忙地算起来：“饭碗是每人1个，菜碗是2人1个，汤碗是3人1个，也就是说1人用1个饭碗，12个菜碗，13个汤碗，合起来1个人用的碗数就是1＋12＋13＝116个。因为总共用了220个碗，每个人用了116个碗，所以客人就是：220÷116＝120位。”

After Du Rui finished speaking, without waiting for the pharmacist Hui Ri to respond, he said, "Since your envoy is proficient in spells, I also have a question here. Please answer it for me. I have a loan of a thousand dollars with a monthly interest of thirty. The lender is 750 yuan, and it will be returned in nine days, what is the interest?"

This question is "Lending Thousands of Money" in "Nine Chapters of Arithmetic". In fact, the question is not difficult, but the pharmacist Hui Ri only has a half-knowledge about the arithmetic, so he was stumped immediately. After hearing the question, the ministers in the palace also heard the question Silently counted, but couldn't figure it out.

Du Rui smiled and said: "Since your envoy doesn't know how to do it, if you sincerely ask me for advice, I will tell you of course!"

Pharmacist Hui Ri heard the words, couldn't help but blushed, and said with difficulty: "Please enlighten me!"

Du Rui smiled and said: "Actually, this question is not difficult. The monthly interest rate in the question is 750 thousand yuan per month. If it is expressed as a percentage, it means: Assuming that the loan period is one month, then the 750 yuan The interest that should be paid on the money is 3x750% = 0.03x22.5 = 9 Wen. However, his loan period is only 30 days. According to the lending routine, if the interest is to be calculated on a daily basis, then it is calculated on 9 days per month. So this The interest payable for 22.530 days is: 9x750 = 0.03x6.75 = [-] Wen, did your envoy understand this!"

Pharmacist Hui Ri listened to Du Rui's answer, and was still checking it silently in his heart. Seeing this, Du Rui knew that he was not convinced, and said again: "I think the envoy thinks this question is too simple and doesn't bother to answer it."

Pharmacist Hui Ri lost face, but he argued forcefully: "That's right, your question is nothing more than that, why is it so difficult to solve!?"

Hearing this, Du Rui hurriedly pretended to be suddenly enlightened, and said, "So that's how it is!"

However, Taizong's monarchs and ministers looked disdainful, and they despised Medicine Master Hui Ri's behavior in their hearts. Even Inugami Mita hid his face with his sleeves, feeling ashamed.

Du Rui remained calm, and said: "In that case, your envoy, please listen to the questions again, the number of chickens and rabbits in the same cage is unknown, and 36 heads are exposed in the cage.

Count fifty pairs of feet, how many chickens and rabbits are there? "

Pharmacist Hui Ri's face was even paler at this time, he thought that he had achieved a small amount in the study of arithmetic and mathematics, and he was invincible in the country, but he never thought that in the land of the Tang Dynasty, a small child would stump him , suddenly full of shame.

Du Rui said: "Actually, this question is not difficult. The first solution is called the method of cutting off the feet. If all the rabbits have two feet hidden, there should be: 72 feet; now there are 100 feet, so they are hidden. If there are 28 rabbits, then the number of rabbits is: 282=14, then 22 chickens are obtained; Solution 144, which is called the method of adding feet, if all chickens grow two more artificial feet, then there are 100 rabbits, now there are 44 feet, there are 442 false feet, so the number of chickens is: 22=14, then the number of rabbits is: 50; Solution 2, which is called the half method below, assuming that all chickens are golden rooster independent, all Rabbits lift their two front feet, so there are 36 feet on the ground. Among the feet on the ground, each rabbit has 36, which is one more than the number of heads. Each chicken has only one foot on the ground, and has 50 heads. If a head has one foot, there are 14 feet on the ground, now there are 22 feet on the ground, and only rabbits have more feet than the head, and each rabbit has one more foot on the ground, so there are 36 rabbits, and 4 chickens are obtained; Solution 144, called the hypothetical method below, assuming that there are rabbits in the cage, there should be 100*2=44 feet, but now there are only 442 feet, the rabbit needs to be removed, and if one rabbit is replaced with a chicken, then 22 will be reduced Feet, now need to reduce 22 feet, need to replace 12 = [-] rabbits with chickens, so there are [-] chickens, [-] rabbits, the next answer, did your envoy understand!"

Although Pharmacist Hui Ri still had the heart to argue strongly, he also knew that with Du Rui's question, even if he insisted on staying, he would be humiliating himself, so he could only hide his face and retreat.

At this time, there was another person in the envoys, who was dressed as a nobleman of the Wa Kingdom: "Your Excellency is too serious, I also have questions, Your Excellency dare to answer!"

Du Rui didn't speak, but just made a gesture of invitation, and the man opened his mouth and said, "What gets hotter and loves it?"

After finishing speaking with a smug expression, Du Rui's eyes widened when he heard the words, his emotions were fighting wits, and he even came up with a brain teaser.

"It's sweat!" Du Rui felt that his IQ was constantly regressing as he fought wits like this.

Seeing that Du Rui answered it so easily, the man said again: "The more you wash, the dirtier it gets. If you don't wash it, people will eat it, and if you wash it, no one will eat it?"

"It's water!"

"What chicken has no wings?"

"frog!"

"Why do you see the lightning first and then hear the thunder?"

"Because the eyes are in front of the ears!"

Emperor Taizong and his ministers had never heard of such an interesting question and answer, so they couldn't help but find it interesting and burst out laughing from time to time.

Du Rui was impatient, and said: "Since your envoy asked, I have a question here, please answer it! Where is a book on the ground that you can't get across?"

Hearing that, the noble young master was stunned.

Du Rui asked himself and answered: "Put it in the corner! Three people, stand in a row vertically. There are five hats, three blue, two red, each wears one, and each is not allowed to see his own color. Then ask What color hat was the first person wearing? He said he didn’t know. Then he asked the second person what color hat he was wearing. He also said he didn’t know. Then he asked the third person what color hat he was wearing. He said I don’t know. I know. Ask what color hat the third person is wearing? Let me tell you, it’s blue! Go back and think about it! What kind of things are known to people who make them, people who buy them, people who sell them, but people who use them don’t? It’s a coffin! Don’t you want to buy one in Chang’an and take it back with you!?”

Seeing that Du Rui couldn't be troubled, the noble young master knew that he was no match, so he had no choice but to back down.

Du Rui was about to return the decree to Emperor Taizong, but the Japanese envoys suddenly raised a Buddhist applause (I don't know whether Buddhism was introduced to Japan during the Zhenguan period, so let's just assume it did).

"Amitabha! The benefactor's wisdom is close to demons, and he can hide it from others, but he can't hide it from the poor monk. Is it true that the poor monk can't see the origin of the benefactor?"