These days, Li Yuanjia wrote another addendum to mathematics.

In fact, it's not a supplement, after all, in addition to the ones that have been taken out, Li Yuanjia still has a lot of mathematical knowledge in his head, and he can even say a concept of calculus, not to mention the knowledge reserves of junior high school and high school, what he still remembers has long been turned into a treasure in the study.

This article was specially written by him for Zhang Cambodia and Li Tai.

Of course, in addition to these two boys, Li Yuanjia will also ask Han Lucheng to save up the manuscript and let the craftsmen at home slowly engrave the engraving - in the future, if he has saved enough for a book, he will print them out and sell them slowly as the seventh volume of mathematics - when he thinks that this set of the world's most advanced mathematical theories will be sent to others to learn in a hurry, and at the same time he will be complained about in Xinhua Bookstore, Li Yuanjia feels aggrieved and uncomfortable.

But there is no way, who let this be China?

The ancestors' mathematical level is not bad, and tools such as arithmetic chips can also meet daily needs, so they are naturally not too interested in foreign Tianzhu numbers. Otherwise, history would not have waited until more than a thousand years later, when China began to lag behind Europe in an all-round way, and was constantly beaten and punished, that Arabic numerals spread and developed with the introduction of science.

Now that some people are willing to learn, Li Yuanjia naturally wants to pay enough attention to it.

So after eating a fairly hearty hot pot, Li Yuanjia sat back on the chair in the study in the afternoon and began to think about what to write in the next "Addendum". In fact, you don't have to think about it, just pick and choose from your own inventory and find something that can be used in this era.

When there is something to do, time flies.

Unconsciously, Princess Han's car drove back to the house, and Fang Fengzhu came directly to Li Yuanjia's study, and then told her about the day's events.

"Have you made all the disadvantages of the kang clear? Did they all understand? ”

Frowning slightly, Li Yuanjia asked lightly.

"Well, it's all clear."

Nodding, Fang Fengzhu said with some apprehension: "And they all understand, but ...... Most people have said that they will make a decision in a short time, but there are a few who want to do it now. After all, this kang is not something that can be done, and it will take more than ten days to say the least, they want to ......"

"yes, I see."

His brows gradually relaxed, Li Yuanjia thought for a while, and nodded slowly: "If you want it, let someone build one for them, anyway, everything will be explained to them clearly, especially when you sleep at night...... The fire is smaller, drink more water, and eat more...... Ahem, forget it, just say the things I said a few more times! ”

Thinking of the vegetable greenhouse that his family had not yet built, Li Yuanjia was very congested, and naturally swallowed back words such as eating more vegetables and fruits.

Fire kang or something, whatever they want.

As a doctor, it is natural for Li Yuanjia to be cautious about the ondol, and this truth is almost the same as the heating in the north in the future. It's okay to get used to it, but if you're not used to it...... If you ask those southerners who spend the winter in the north for the first time, are many of them having cracked lips? Does it have a sore throat and a greater chance of catching a cold?

Modern people in the 21st century must have a much stronger physique than the ancients.

So what Li Yuanjia is afraid of is that once these people have a fire kang, it will be winter...... Especially in the cold winter, you will definitely be greedy for the temperature on the kang, and if you can't say it, there will be such and such problems.

But......

As it just said, if you have to build it, build it!

Although there are some worries, after all, they are a group of women from powerful families, and the magnates of the Tang Dynasty basically have a common characteristic, that is, they are from good backgrounds, and there are almost no poor people.

In other words, you should understand more or less.

So after nodding, Li Yuanjia deliberately explained: "But it's just someone else, Changle and Yuzhang, you explain a few more times...... I heard that the two of them are a little weak, so don't be careless! ”

"Yes, my lord, don't worry."

After biting her lower lip, Fang Fengzhu smiled and nodded.

She also understood what Li Yuanjia meant, after all, even if something went wrong with the fire kang for others, King Han's identity could bear it, but if something happened to Yuzhang and Changle......

While nodding, Fang Fengzhu secretly remembered this matter in her heart.

Seeing her thoughtful look, Li Yuanjia smiled slightly and said, "By the way, how is today?" Is the club still deserted? ”

"Huh? How can it be?! ”

As soon as Fang Fengzhu heard this, he was immediately unhappy, and his eyes widened: "Even Princess Changle is here, how can the club be deserted?" Let me tell you, there were fourteen people at nine in the morning...... And after lunch, we went to three or four, and we set up three tables for the mahjong table alone! ”

“…… Playing mahjong again? ”

Thinking of what Li Shimin said when he summoned him, Li Yuanjia immediately had a headache.

This thing is just too powerful!

The women of the club have quickly proved this, and it is conceivable that this thing will definitely spread throughout Chang'an at a faster speed than cards - cards also use paper, especially the requirements for paper are relatively high, and the cost is relatively expensive, but if you play mahjong, you can use ivory carving, but you can also play with some wood!

Thinking of the realization of national mahjong in the thirteenth year of Tang Zhenguan, Li Yuanjia couldn't help but shudder.

Seeing his headache, Fang Fengzhu was a little worried, and asked cautiously, "King, ...... That's fine, right? ”

"Hehe, what's the problem? All right. ”

Waving his hand, Li Yuanjia smiled and shook his head.

It's like this, he has nothing to regret, and if Mahjong can help promote Arabic numerals, even if it is scolded by the emperor a few more times, it doesn't seem to be a big deal?

After listening to his words, Fang Fengzhu was very happy.

She didn't think about it so much, she just felt that because of mahjong, this ondol, plus the previous sauna, big landlord or something, now the club is really thriving, and people come every day...... Although sometimes there are few people, that is, there are three or two kittens, but after all, someone comes, right?

And everyone [5200] came not only to play, but also to study mathematics seriously.

After all, starting from next year, if you don't know a little, you won't have the qualifications to join, and everyone is willing to learn means that they are very recognized by the club, and they will definitely join next year!

For Fang Bong-joo, there is nothing more enjoyable than this.

She was happy here, and Li Yuanjia was also happy, and said with a smile: "Since the club is so lively, then I don't have to worry about it anymore, right?" Hehe, it just so happens that I have something to do next, and I'm afraid I won't be able to get out of it in a short time......"