Mubashaf's expression was a little stunned, he really didn't expect this handsome young man to really answer this question. He looked at Yu Wenming in front of him, and his expression changed slightly for a while.

The ministers in front of the palace are all scheming people, and when they see Mubashaf's expression, how can they not guess the reason.

Even the eldest grandson Sheng was overjoyed in his heart, and smiled at Mubashaf: "Mubashaf, are you convinced now?" ”

"Humph! There is also a third question, if Yuwen Gongzi can really answer the third question, I, Mubashaf, will definitely not break my promise, and I will definitely keep my promise! Mubashaf snorted coldly, and then looked at Yu Wenming, with a thoughtful look in his eyes, obviously thinking about how to ask the third question.

After a moment, he apparently had the subject in mind, and then he said with his hands behind his back: "In the east of our country, there is a kingdom called Persia, and the king of this country likes to come up with strange questions to embarrass his ministers. One day, on a whim, he asked the ministers to say something that was not true or false. It's hard for these ministers, because what they say is either the truth or the lie. No one can say anything that is not true or false. ”

"Later, when the king finally got tired of it, he commanded: 'If you tell the truth, you will be fined twenty denarii, and if you tell a lie, you will be fined ten denarii.' Now you're going to take another turn! As a result, the ministers were naturally unable to say anything that was not true or false, and were punished with silver coins. But when it was the king's horse's turn, the horse had an idea and said something that was not true. Excuse me, what is this untrue and untrue statement? Mubashav said confidently. Obviously, he thinks that this question is far more difficult than the previous two questions, and it is difficult for anyone to answer it.

Everyone in the main hall frowned and pondered, obviously this is not true or false, it is really difficult to stump people. Changsun Sheng is also a little worried, Mu Bashaf's three questions, Yu Wenming has already solved two of them, but don't drop the chain on this third question! Otherwise, all the work will be wasted!

Yu Wenshu and Yu Wenhua and the father and son, originally planned to find a way to remind Yu Wenming if they thought of the answer. But now it seems that they have no clue at all.

Yu Wenming showed a victorious smile on his face at this time, secretly thinking that this question was actually a brain teaser. Although it was a little more difficult for the ancients, it was not a big problem for him. So, he spoke eloquently: "I suppose that the horse's words to the king must have been: 'I will be punished by your majesty with ten pieces of silver!'" And if this is true, according to the king's rule, he shall be punished with twenty pieces of silver, but what he says is only a penalty of ten pieces of silver, so it is not true." ”

But if the horse is false, he shall be punished with ten denarii. But if he was really punished with ten silver coins, wouldn't that just show that he was telling the truth? So, in this way, what he said is true! Yu Wenming said calmly.

As soon as Yu Wenming's words fell, a whisper sounded in the hall, and everyone's faces showed a look of consternation. Apparently amazed at his ingenious inference and response.

If there were still people who doubted whether it was really Yu Wenming's solution to the problem, even Yang Xuangan and others thought that Yu Wenshu found a staff member to solve the problem, and then reported it in the name of his grandson, trying to show off in front of the saint. No one doubts that anymore.

Because the difficulty of these three questions is far beyond the previous three questions. Yang Guang secretly thought, if Yu Wenming hadn't solved it on the spot, even if he found someone to solve the problem, I am afraid that it would not be possible to succeed for more than half a year.

He smiled slightly at this time and said to Mubashaf: "Mubashaf, you should have nothing to say now!" Our Great Sui is indeed the most culturally advanced and developed country in the world. You don't have to go to Goryeo to verify! ”

Mubashaf's face turned blue and white for a while, and he had no choice but to say: "The Great Sui is really capable of producing many people, and I admire it, I will definitely send a thousand great horses and five hundred black steel knives to the Great Sui within three years according to my previous promise, and I will never break my promise!" ”

Yang Guanglong Yan Dayue, when he ordered Changsun Sheng to come down, he finalized the details of the agreement with Mubashaf, signed the contract as soon as possible, and could not afford it.

Changsun Sheng naturally couldn't ask for it, and he also wanted to finish this matter earlier, so as not to cause extraneous branches.

However, Mubashaf obviously refused to admit defeat, he rolled his eyes at this time, and continued: "Dear Your Majesty of the Great Sui Kingdom, your country is indeed rich and profound in culture, which makes the envoy admire, but it is not enough to think that the Great Sui is the most advanced and developed country in the world, at most it can only show that your country's culture and our country are at the same level." Unless someone in your country can solve the problems that have plagued our country and the Byzantine Empire, the Frankish Kingdom, and the Persian Kingdom for many years, I will recognize the Great Sui as the most culturally advanced country in the world. ”

When Mubashaf said this, everyone's faces suddenly changed. Although they don't know what the Byzantine Empire, the Frankish Kingdom, and the Persian Kingdom are, they must not be much different from this great food. The problem that no one in the four countries has been able to solve so far, you can imagine how difficult it is.

However, since Mubashaf has already raised it, he cannot ignore it. Yang Guang was stunned for a moment, and had no choice but to say: "Then tell me, what is the problem?" ”

Mubashaf said with a mysterious smile on his face at this time: "I wonder if your country knows prime numbers and composite numbers?" ”

All the ministers in the main hall showed a blank look on their faces, and after a while, Changsun Shengfang frowned and asked, "In my Great Sui, there is only the saying of numbers, but I don't know what the prime and composite numbers you mean when you say it?" ”

Mubashaf was overjoyed when he heard this, and thought that the Sui people did not even have the concept of prime numbers, and it seemed that it was probably impossible to solve this problem.

He then smiled and said, "It seems that your country may have studied this aspect relatively shallowly...... Prime numbers in China refer to numbers that can only be divisible by one and themselves, such as two, three, five, seven, etc. A composite number is a number that is divisible by other numbers in addition to one and itself, such as four, six, eight, nine, etc., ......"

After Mubashaf explained for a long time, Yang Guang and the Sui courtiers who were present finally understood.

After Yu Wenming heard about it, he was secretly shocked in his heart, he didn't expect that Da Shi would be studying prime numbers and composite numbers in this era. And a whole concept has been formed. It seems that China's theoretical research in arithmetic, physics, chemistry, and other natural sciences is indeed inferior to others.

At this time, Mubashaf said aloud: "More than a hundred years ago, the deceased king of our country, Harimer, wrote a speculation in his diary, and he said that he had come up with a way to prove that prime numbers and composite numbers are infinite. However, when he wrote this, the diary had just been written, and there was no way to write down the proof. And even more unfortunate: shortly after him, a fire broke out in the palace, many materials and books were burned, and the chamberlains searched for a long time but could not find the proof of what His Majesty Halimer had written. Therefore, this has become a difficult problem that has always plagued our country. For more than 100 years, countless people in our country and neighboring countries have been looking for answers, but they have never found them! ”

Speaking of this, he bowed to Yang Guang and said, "Your Majesty the Great Sui Kingdom, I know that you are about to fight Tuyuhun, and you are in urgent need of high-quality war horses and high-grade weapons!" If we can help us solve this problem, our country will establish a long-term trade relationship with your country, and even form a formal alliance. And my country's unique big food war horse and black steel knife, if they are shipped to your country, they will only be sold at the market price of our country, and they will never ask for a sky-high price! ”

When the ministers heard this, they were all moved. Especially Yang Guang and the generals present, there was a golden light in their eyes.

They all understood by now that the Great Eater War Horse was the best war horse they had ever seen. Mubashaf's horses were unanimously considered by the palace officials to be no different from the legendary bloody horses. As for the black steel knife he presented, it was easier to cut several swords in the palace that were known as divine weapons.

If you can establish a long-term trade relationship or even an alliance with the Great Food, you can get a large number of Great Food War Horses and Black Steel Knives at a parity price, wouldn't it be possible to increase the combat effectiveness of the Sui army by two grades? Don't talk about the extermination of Tuyuhun, even the extermination of Turks and Goryeo, I'm afraid it is not a problem.

Ten years ago, when Yang Guang was still the king of Jin, the Sui army attacked Goryeo, but after a defeat, they came back in disgrace. This has always made Yang Guangyin a lifelong shame. If you can get these good horses and weapons, and in time, Yiliang will train the government army. Why worry about the immortality of strong enemies such as Goryeo, Turkic, and Tibetan?

So, he hurriedly asked, "Ladies and gentlemen, can anyone come up with an answer to this difficult question?" ”

Yang Guang asked several times, but no one dared to answer. He was slightly disappointed, but it was indeed too impatient to think that this question was a question that several countries such as Dashi could not answer for hundreds of years, and it was indeed too impatient for his ministers to answer it immediately.

So, his gaze naturally turned to Yu Wenming, expecting him to answer this difficult question.

Yu Wenming took a deep breath, of course he knew that proving that prime numbers are also infinite, is a famous problem in the history of mathematics. As far as he knew, it was only in the eighteenth century that the famous mathematician Euler proved successful. So it's no wonder that several countries such as Dashi, Byzantium, and Franks can't prove it nowadays. Fortunately, he had seen the proof of infinity of prime numbers in a book called "History of Mathematics", and he vaguely remembered the method.

"Lord Mubashaf, although this question is a bit difficult for Da Shi, it is not a difficult problem for my Da Sui." Yu Wenming said eloquently.

"To prove that prime numbers are also infinite, it can be proved by the method of counterproof. We can start by assuming that there is one largest prime number in the world, and all prime numbers are smaller than this prime number. Then we multiply two by three, then multiply by five, then multiply by seven...... And so on, multiplying all the way to the largest prime number, presumably this number must be much larger than this largest prime number, right? Yu Wenming asked Mubashaf rhetorically.

Mubashaf figured this out after a moment's thought, and he nodded and said, "That's true, so what should we do next?" ”

"Then let's add the product to one, and won't this number be divisible by all the primes that now exist?" Yu Wenming smiled slightly.

While the ministers of the court were still thinking about what was going on, Mubashaf suddenly changed color, and what Yu Wenming said was indeed right.

So, either the number itself is a prime number, or it is divisible by a number larger than the largest prime number previously thought. Both of these conjectures, either way, rejected the previous inference that there was a maximum prime number. Thus, prime numbers are also infinite, just like composite numbers and integers, infinite! Yu Wenming said solemnly.

Mubashaf pondered for a long time, but his face was pleasantly surprised. Because he found that according to the proof method of Yu Wenming, this world-famous difficult problem was really solved.

Although Yang Guang didn't understand too much, he looked at his face and saw the change in Mubashaf's expression.

He laughed and said, "Mubashaf, I wonder if you are still satisfied with the proof of Little Brother Yuwen?" ”

"Satisfied! So satisfied! Mubashaf also had a happy expression. For if he came to the East, he would find a way to prove it, and when he returned, he would be rewarded by the king, and he would not be overwhelmed by the reward of finding allies in the East.

"Good! Yu Wenming has made such a great contribution to my Great Sui, and he is out of the queue to listen to the seal! Yang Guang said with a smile on his face at this time.

Yu Wenming hurriedly stepped forward to bow down. At this moment, Yang Guang's voice came to my ears: "Yu Wenming, I heard that you had an outstanding performance in the poetry competition before, and gave very good suggestions for my new imperial examination in the Great Sui. I've always wanted to reward you, but I haven't found a good opportunity. Now you have solved the problem of the Great Food Envoy and solved the problem for my Great Sui. I'm so happy......"

"However, you are still young, and it is not appropriate to seal it too much. Now I have temporarily appointed you as a regular attendant of Guozi Temple, you can study more in Guozi School first, and when you are a few years older in the future, I will promote you to officially enter the court as an official! Yang Guangzheng said.

When Yang Xuangan heard this, he knew that it was going to be bad, but he didn't expect that not only Yu Culture and this unlearned and unskilled person could live in the high hall, but even his twelve-year-old illegitimate son could hold an official position in the court, which was very disadvantageous to himself!

It's just that Yu Wenming's performance is indeed too prominent, first with suggestions for the imperial examination, and then with the credit for solving the problems of the Great Food Messenger. And he's only twelve years old, so he can't find a stain on him.

Yu Wenming was also overjoyed, and hurriedly stepped forward, kowtowed heavily and said, "Xiaomin is willing to serve Your Majesty!" ”

And at this moment, the surrounding ministers also looked at him with envious expressions.

Secretly thinking about the children in his family, I am afraid that he is still playing every day at the age of twelve, and this Yu Wenming has actually entered the court as an official. Although this Guozi Temple is only a yamen responsible for the official education of the imperial court, and has no real power, it is also one of the eleven temples in the five provinces, six departments and eleven temples of the imperial court.

It is the modern equivalent of the Ministry of Education. The following four departments of Tongguozi, Taixue, Simen and Shushu, Taixue Changshi is equivalent to the deputy director of the Department of Higher Education under the Ministry of Education today. Although this position has no real power and oil, it is an official position of Zhengbapin. In other words, Yu Wenming can no longer participate in the imperial examination and family recommendation, and is directly promoted by the emperor.

And many ministers in the court who are good friends with Yuwen Shu also sang praises and praised the saints as wise. There are also many people who believe that three generations of the Yuwen family have entered the court as officials, and Yuwen Shi is a holy concubine. In the future, the Yuwen family will become the most powerful family in the Great Sui, and I am afraid that it is just around the corner. So they stepped forward to congratulate, which made Yu Wenshu and Yu Wenhua and their originally tense faces suddenly relaxed, and thanked them one by one.

Subsequently, Yang Guang announced that two days later, the army would officially set out on an expedition to Tuyuhun. Yu Wenshu, Li Jing and others are among them. This was how the war machine of the Great Sui was slowly set in motion.