"It's true! But I want to see it with my own eyes, I don't know if Gongjin will dare? Xiang Han smiled slightly, and had such an idea in his heart.

"Of course, you can do it!" Zhou Yu nodded, not afraid of Xiang Han's test at all.

Xiang Han thought about it, smiled slightly, and asked Zhou Yi to prepare his pen and ink.

Lifting the pen, I saw Xiang Han draw a nine-square grid on a piece of cloth.

"Nine palaces count, I'm sure you've heard of it, right? Here is a nine-square grid, 1 to 9 a total of nine numbers, you fill in these nine numbers, to ensure that the nine-square grid horizontal, vertical, and oblique three numbers add up to the result of all equal! Xiang Han smiled slightly and came up with his first question.

"This ......"

The arithmetic of the nine palaces is the earliest proposed in the "Zhou Yi", and its value is not only confined to arithmetic, but also calculated in the nine palaces, and the celestial phenomena are recognized, which has a wide range of application value in ancient astronomy, calendar, agricultural and animal husbandry production and social life.

Of course, this question from Xiang Han is one of the various problems of the Nine Palaces of Arithmetic.

Although this question was very simple in later generations, it could be regarded as a difficult problem at this time in the late Han Dynasty!

Zhou Yu frowned, Jiugong didn't study it in depth, but this question, he believed that he could make it, wasn't it nine numbers?

"Wait for me!" As he spoke, Zhou Yu picked up the pen and calculated quickly on the cloth.

Xiang Han was not in a hurry, nor did he speak, but just looked at Zhou Yu quietly on the side, waiting for Zhou Yu's calculation results.

"It's done!"

Finally, after nearly a quarter of an hour, Zhou Yu put down the pen in his hand and presented the result in front of Xiang Han.

After a cursory glance, Zhou Yu's answer was the standard answer.

This can't help but make Xiang Han a little admired, this Zhou Yu really looks like a prodigy.

"Huh? Don't you even check the math to know the answer? Seeing that Xiang Han only glanced at it and nodded, Zhou Yu was a little puzzled, could it be that Xiang Han knew the answer with just one glance?

"Of course, such a simple question, do you still need to check it?" Xiang Han smiled slightly, reached out to pick up the pen, and drew a nine-square grid again, "You see, two or four is the shoulder, six or eight is the foot, three on the left and seven on the right, one on the nine, and five in the center." In this way, the problem just now is solved! ”

Xiang Han directly moved out the mantra of Zhen Luan during the Northern and Southern Dynasties.

"Wow! It's amazing! Zhou Yu nodded in surprise, and suddenly realized that this question was so simple!

"Are you interested in doing the next question?" Xiang Han is now like a math teacher in an elementary school, and he has just ignited Zhou Yu's interest.

"Yes, yes, yes!" Zhou Yu nodded again and again.

"Then you listen: there is a big cage, there are chickens and rabbits in it, but I don't know how many there are, there are 27 heads, just look at the feet, there are a total of 84 legs, so, how many chickens and rabbits are in this cage?" Xiang Han read the title to Zhou Yu as he wrote.

This......

After Zhou Yu got this question, he immediately frowned, how should this question be calculated? It feels so hard!

That's right, the problem of chickens and rabbits in the same cage is one of the famous typical interesting questions in ancient times, recorded in the "Sun Tzu Sutra", which was written in the 4th and 5th centuries AD.

Therefore, people have not heard of the problem of chickens and rabbits in the same cage.

Zhou Yu started the calculation, but after calculating for a long time, he couldn't figure it out.

Anyway, the current Zhou Yu is just a ten-year-old child, even if he is a genius, it is difficult to answer such a question for a while!

"I ...... I can't do it. ”

After a while, Zhou Yu spoke.

In fact, it wasn't that Zhou Yu gave up, but two quarters of an hour had passed, and he didn't have a clue yet, not to mention, everyone looked at him and didn't even speak, he also knew that this was not good, so he took the initiative to admit defeat.

"Hehe, I don't blame you for this, after all, this question is indeed a bit difficult." Xiang Han smiled and did not continue.

"So what's the answer to this question?" Zhou Yu asked suspiciously.

"I don't know, I'm just asking such a random question!" Xiang Han smiled slightly.

"Huh?"

Obviously, Zhou Yu was a little disappointed.

"However, I can teach you how to do it, and then you will know the answer!" Xiang Han smiled slightly.

"You see, what we know now is that rabbits have four legs and chickens only have two, right?"

"Hmm!"

"So, let's make all 27 chickens and rabbits lift two feet, so how many feet are left?"

"27 times 2 is 54, and 84 minus 54 is 30 feet!"

"You think, after the rabbit lifts two feet, there are still two legs left, but the chicken is different, after the chicken lifts two feet, does it all sit on the ground?"

"Hmmm! I understand! These 30 are all rabbits! That's 30 divided by 2, there are 15 rabbits, and there are 12 chickens! ”

"Yes, yes, I learn so fast!" Xiang Han smiled and nodded, before he finished his thoughts, Zhou Yu had already come up with the answer, it seems that if the guidance is right, this Zhou Yu's future is limitless!

"Father!" Zhou Yu seemed to think of something, returned to Zhou Yi's side, and whispered a few words to Zhou Yi.

"You've really decided?" Zhou Yi asked in a deep voice.

"Well, the kid has decided!" Zhou Yu nodded, like that, very solemn.

What are the father and son studying?

Xiang Han looked at them with some doubts, picked up the tea on the side and took a sip.

Soon, the two stopped communicating, and Zhou Yi looked at Xiang Han with a smile: "Zimo, look, Gongjin wants to worship you as a teacher, I don't know what you think?" ”

"Poof!"

The sip of tea that had just been drunk in his mouth, Xiang Han hadn't had time to swallow it, but now it was all squirting out.

What is the situation, he did want to fool Zhou Yu, but it was just two questions, so he wouldn't be apprenticed, right?

"Seriously?" Xiang Han was a little incredulous.

"That's right, the dog wants to worship Zimo as a teacher, so I also ask Zimo to fulfill it." Zhou Yi nodded.

"That's right, please do it sir!" As he spoke, Zhou Yu knelt directly in front of Xiang Han.

In fact, what Xiang Han didn't know was that Zhou Yu worshipped Xiang Han as a teacher, firstly, because the two questions of Xiang Han just now seemed to open the door to a new world for Zhou Yu, and secondly, more importantly, he wanted to study with Sun Ce, for some reason, he wanted to make a friend like Sun Ce, if he parted, he would be very sad.

"Okay, then you can kowtow three times like Bo Fu, and give me a cup of tea, and that's it!" Xiang Han nodded.

"Thank you, Master, for making it happen!" Zhou Yu didn't say a word, directly kowtowed three times, and then gave Xiang Han a cup of tea.

"Well, you will also be my disciple from now on, but there is an ugly thing I want to say earlier! Whatever I command you, you must obey it! There's no need to disobey, you know? Xiang Han opened his mouth and said very solemnly.

"Understood!" Zhou Yu nodded without hesitation.