As soon as you enter the Houmen, it is as deep as the sea, this sentence is really true. Pen & Fun & Pavilion www.biquge.info Zhang Cang is not a Houmen, to put it bluntly, he is a squire with some prestige in Yangwu, and he is also a royal official in the officialdom, and there is a difference of 108,000 miles from Houmen! This mansion is such a spirit, which shows the luxury of the Houmen mansion.

Li Yan took Li Xiao and Zhang Cang around and around, and when they were dizzy and dizzy, they finally turned into a beautifully built house.

Zhang Cang did not take them to the guest room, but took them directly into the study.

In this era, the study room is generally not accessible to everyone, and such an aristocratic family pays more attention to these. Meetings are usually held in guest rooms, unless they are close friends or like-minded colleagues who share common research.

Li Yan saw Zhang Cang bring himself into the study, and couldn't help but have some doubts in his heart.

The furnishings of the study are very simple, a couch in the middle, a few bookshelves of pear blossom wood against the wall, and the bookshelves are full of all kinds of bamboo slips, wooden slips, and silk books.

Zhang Cang saw the doubts in Li Yan's heart, so he asked him to sit down and said: "Zhang Gongzi doesn't have to be confused, I heard Wei Xiaotian say that Gongzi is proficient in arithmetic a few days ago, and I am happy to see Hunting, so I can't help but invite him to teach one or two!"

Li Yan also guessed a few points in his heart, but he didn't expect that he was so interested in arithmetic and so grand about himself.

"Mr. Zhang has won the prize! Adults are pedantic, and the kid can only be regarded as an occasional dabbling in arithmetic, how dare he be called proficient in front of adults! ”

Li Yan didn't dare to hold it up, he had read some ancient arithmetic problems on the Internet before, and some of the questions he couldn't understand or solve! Now, although he has studied writing with Zhang Liang for a period of time, there is no problem of not being able to understand it, but there are still some problems that he can't solve as a person who has been away from school for many years.

"Li Gongzi doesn't have to be too humble, come, let's see how to solve this problem first?"

Zhang Cang said and picked up a page of bamboo slips on the table in front of him and handed it to Li Yan, obviously the bamboo slips had been prepared for a long time this night!

Li Yan took the bamboo slip, only to see that the bamboo slip was written like this: Fangtian (to the boundary of the Yutian domain) is now fifteen steps wide, from sixteen steps. Q: Geometry for the field?

Li Yanmo rubbed the bamboo slip in his hand, thinking that since Zhang Cangjing studied arithmetic, there was no reason why such a simple Fang Tian problem would not be, he was testing himself to see if he was really proficient in arithmetic as Wei Xiaotian said.

This Zhang Cang really underestimated himself!

"One acre!"

Li Yan blurted out without thinking.

Zhang Liang dabbled in a wide range of things, and Li Yan studied literature with him, and still understood some of the units of measurement in this era, knowing that two hundred and forty steps was one mu. The multiplication of fifteen steps and sixteen steps is two hundred and forty steps, which is exactly one acre.

This kind of simple elementary school math problem is of course not difficult for Li Yan, it is a piece of cake.

Zhang Cang was obviously stunned, he heard that Li Yan was proficient in arithmetic, and his calculation speed was extremely fast, although he was mentally prepared, he was still suppressed, he didn't expect Li Yan's calculation speed to be so fast.

In this era of extreme lack of books, ordinary people do not know words, that is to say, the vast majority of people are illiterate, only a very small number of wealthy families have the opportunity to read and write, even some well-educated people are only studying some ways of governing the country, or are obsessed with mountains and rivers hidden in the mountains and forests, will regard arithmetic as a side study, few people dabble, like Li Yan is so young to be proficient in arithmetic is indeed not many, Zhang Cang is not amazed, and Zhang Cang is not ashamed.

"Zhang Gongzi is really a celestial, I, Zhang Cang, have studied arithmetic for half my life, but I am not as good as you! It really made Zhang ashamed! ”

Zhang Cang's face was ashamed, but he was honest and sincere!

"Master Zhang doesn't have to be too humble, the kid just knows the solution to this kind of problem, it's just a coincidence!"

Although Li Yan didn't know that Zhang Cang was going to edit "Nine Chapters of Arithmetic" later, he could feel that he had a deep study of arithmetic, so he didn't dare to hold it up, so he hurriedly gave a humble gift!

"Zhang Gongzi is really modest, take the liberty to ask, how did Gongzi solve it?"

Zhang Cang is very modest, his body is very low, and he is a little embarrassed!

In this era, you can't take the liberty of asking others some skills, each industry has its own unique secret skills, unless it is an apprentice, otherwise it is their own biological children who are also passed on to men and women, and it is a taboo in the industry to ask others about skills, of course, this is not a skill, but it is widely used in many fields, so Zhang Cang put his body very low, and he was a little embarrassed.

Li Yan didn't know this, even if he knew that he grew up in the era of the big explosion of knowledge, he would not cherish himself, and he would tell him in detail without reservation.

"Actually, this is a square area problem, and the answer can be obtained by multiplying the product." Li Yan replied.

"That's how I calculated the answer, but the speed can't catch up, how did you come up with the answer so quickly?" Zhang Cang then asked again.

Li Yan smiled and replied, "I have an ancestral formula, as long as I use this formula, all multiplication problems can be quickly derived."

Zhang Cang's face was full of regret, but he didn't ask any further, ordinary ancestral things will not be passed on, although he knew that this mantra was very helpful to his arithmetic research, and he was eager to know this mantra, but he knew that he couldn't ask each other, that would break the rules!

What he didn't expect was that Li Yan then spoke again.

"This formula, I'll make it ninety-nine, so let's write him down and send it to you, and I won't be able to say it clearly for a while!"

Zhang Cang was stunned when he heard it, and then he was overjoyed, he was ecstatic, and he almost didn't jump up like a child.

He hurriedly got up to find the blank bamboo slips, and when he walked halfway, he seemed to remember something, turned back and bowed deeply to Li Yan, and then went back to happily take the pen and ink bamboo slips.

He didn't expect Li Yan to be so generous, he would write this multiplication formula to himself, he could imagine its importance to himself, its importance to society, if it is promoted for the military, agriculture, commerce is undoubtedly of great significance, unceremoniously it can be said that it is a milestone!

Li Yan looked at Zhang Cang's childlike excitement and laughed silently.

Soon Zhang Cang prepared everything, Li Yan picked up the pen, and without thinking, he wrote it in one go.

This elementary school memorized the multiplication formula, Li Yan doesn't need to think, it can be said that he will come with a pen.

Zhang Cang carefully took the bamboo slip handed over by Li Yan, blew the ink that had not yet dried on it, and looked at it carefully.

Zhang Cang is an extremely smart person, he understands at a glance, some of these mantras he knows, and often uses, but there has never been such a complete summary of the system, it has a total of forty-five sentences from one to one to ninety-nine eighty-one, one sentence is a lot, one sentence is not much, and it is catchy and easy to memorize.

If you memorize it in your mind, Zhang Cang can imagine how fast it will be to calculate in some multiplication problems.

After Zhang Cang read it, he gave Li Yan a deep salute.

"Li Gongzi really has a family history, this multiplication formula can be said to be a milestone in arithmetic, he will definitely play a great role in promoting the development of arithmetic, and the help to me is unimaginable!"

Zhang Cang's attitude is sincere, and his face seems to exude holy light!

"My family is just a rural family in a mountain village that makes a living from hunting, where can I talk about the origin of family education? Now I'm the only one left because of the war! ”

Li Yan's voice was a little low, and as he spoke, he remembered his parents who were more than 2,000 years apart. People say that the biggest tragedy in life is the loss of a child in old age, and their parents should not have come out of their grief by now! They are still sparing no effort to find themselves!

Now Li Yan's biggest tragedy is that he is obviously still alive, and he still knows that his parents are looking for him, but he can't go back, and the time gap makes him never see them again!

Zhang Cang found the deep pain in Li Yan's eyes, and knew that he reminded him of something painful, so he hurriedly apologized.

"I'm really sorry, I reminded Li Gongzi of the sad past!"

After Li Yan heard it, he knew that he had lost his temper, so he quickly collected his mood.

"It's nothing, it's that I think of my deceased parents, and I have a bit of a gaffe, which makes Master Zhang smile!"

After speaking, Li Yan paused and continued.

"I know that Master Zhang has doubts, this multiplication formula was originally left by a Taoist priest who my grandfather saved in his early years."

Li Yan lied and didn't make a draft, and made up a story to prevaricate.