Seeing that Changsun Chong, Wei Shuyu, Qin Huaidao and others all opened their mouths to call Zong Xiu 'Master', Chai Lingwu's face became even worse.

He felt betrayed.

Chai Lingwu gritted his teeth and said: "I admit that you are quick thinking, refined and arithmetic, but if you want to rely on a time-wasting arithmetic to convince me, it is absolutely impossible." ”

Zong Xiu yawned and said, "What? Didn't you say it was a small account of a few pennies before? How did it become a waste of time in arithmetic now? ”

Kong Yingda hurriedly became a peacemaker: "Assistant Professor, it's not too early this day, why don't you tell them about the logic of the question just now." ”

During the Tang Dynasty, arithmetic ranked at the end of the six schools, and the most respected by the current scholars were poetry and articles, and a subset of classics and history.

However, the literati admired the subset of classics and histories, and the poetry and songs, but this did not mean that they did not need to learn arithmetic.

Officials, in particular, must have a certain foundation in arithmetic, and if they are poor in arithmetic, they must be specially trained for a period of time before taking office.

Otherwise, you can't even read a tax account book, so how can you be a good parent official.

Qin Huaidao and Wei Shuyu said in unison: "Please also ask the master to give advice." ”

Zong Xiu did not agree immediately, but looked at Chai Lingwu directly.

"Master Chai, why don't we make a bet!"

"What are you going to bet on?"

Chai Lingwu asked coldly.

"How about I bet that I don't need to do the math to figure out the answer to the question just now?"

Chai Lingwu said angrily: "The question is yours, you must know the answer, what kind of bet is this?" ”

Here it comes!

Same as I thought.

That's what Zong Xiu wants.

Only when Chai Lingwu said something similar could he proceed to the next step.

"Haha, then let's change the way of gambling. Bet I can teach you how to solve the answer to that question without counting chips in a stick of incense. ”

"Don't worry, I won't tell you the answer directly, only the rules! If I can't solve it according to my method, what if I lose? ”

Jong Xiu laughed loudly.

Qin Huaidao, Changsun Chong, Wei Shuyu, Fang Yiai, Du Gou and others were all shocked.

They have learned how difficult the question is.

For two whole hours, Wei Shuyu, who was the best at arithmetic, only counted the sum of one month, which was already an astronomical amount.

Now Zong Xiu actually said wildly, saying that in a stick of incense, teach them to solve the law, and there is no need to calculate.

Dream it!

Several small princes looked at Zong Xiu with questioning eyes.

Kong Yingda is no exception.

He is different from these small princes who have just entered the country for a few years, as a great Confucian in the world, Kong Yingda's attainments in arithmetic are also very high.

Like ordinary arithmetic, it is not difficult for him not to do arithmetic, but the question just now......

Kong Yingda said in a deep voice: "Sect Assistant Teacher, what you said is true? ”

Zong Xiu said: "It really can't be true!" What is the difficulty of summing in equal proportions? ”

"Good! If you can really teach you how to solve the problem in a stick of incense, I will personally fold it and reward you! ”

After Kong Yingda finished speaking, he walked to the bookcase below, sat on the futon, and turned his face back like an old boy, waiting for Zong Xiu to speak.

"Come on!"

Zong Xiu shouted.

The six scholars below, you look at me, I look at you, but they didn't move.

Jong-so: ......

He wanted to be handsome, but he failed.

Qin Huaidao hurriedly snatched the book basket carried by his scholar, took out the wolf's hair, and handed it over respectfully.

Wei Shuyu was not far behind, walked to the bookcase with an inkstone, and said, "Master, I'll sharpen ink for you." ”

"Hehe, it's a bit of a student."

Zong Xiu took the wolf pen, dipped it in ink, and splashed ink on the rice paper spread out by Qin Huaidao, writing wildly.

Qin Huaidao and Wei Shuyu stood next to Zong Xiu, and they were confused when they saw the strange characters on the paper.

"That's it!"

After Zong Xiu finished writing, he threw away the brush, pointed to the white paper full of words and said, "You two, pick it up and hold it up." ”

"Yes, Master."

Qin Huaidao and Wei Shuyu respectively carried the two sides of the white paper and acted as a temporary blackboard shelf.

Kong Yingda frowned slightly: "Sect assistant, these symbols are ......"

When asked by Kong Yingda, Zong Xiu remembered that he wrote the numbers of later generations, that is, the Arabic numerals invented by the ancient Indians.

Not to mention that the Arabic numerals of this period are still the original simplified version, which has not yet been introduced to the Tang Dynasty. Even if it came in, no one knew the formula he wrote.

Zong Xiu coughed lightly, hiding the embarrassment in his heart, and said cheekily: "These are some symbols that I created myself, which are used to replace cumbersome text writing and facilitate calculation." ”

"Homemade?" Kong Yingda was taken aback at first, and then asked, "Is it available?" ”

"Of course it works, and it's accurate!"

After Zong Xiu briefly described the Arabic numerals from 0 to 9, he briefly said two words about the carry method at the back, everyone's faces changed, and their eyes were full of shock when they looked at Zong Xiu.

In the year of the weak crown, he created a number that replaced the written word, and it could withstand scrutiny, such an amazing and brilliant person was comparable to Cangjie.

Especially Kong Yingda, her eyes were shining, and her wheezing became heavy.

When it comes to Kong Yingda's knowledge, the realm of seeing things is naturally higher than that of ordinary people. He has already seen what kind of changes this kind of simple, easy-to-learn and easy-to-understand number symbols will bring to the entire Datang.

Qin Huaidao and Wei Shuyu were even more cautious carrying both sides of the rice paper, as if there was some rare treasure on it.

Fang Yiai, Du Gou, and Eldest Sun Chong's gaze at Zong Xiu became even more intense.

Even the most arrogant Chai Lingwu had jealousy in his eyes.

The cow has blown it, and Zong Xiu is also a little embarrassed.

"It's just a few carving insect skills, it's hard to wait for the elegant hall. Let me start with the solution to the problem. ”

Jong Xiu pointed to the white paper full of formulas, and disguised his embarrassment by changing the subject.

"Take the number of the first seven days as an example, explain the rules, whether you can understand it or not, it's up to you."

"It's a simple formula for summing a series of proportional numbers."

"Look here, 1, 2, 4, 8, 16, 32, 64. Have you noticed any patterns? ”

The eldest grandson rushed to reply: "The next day is twice as much as the previous day." ”

"Not bad."

Zong Xiu nodded.

"Like this problem, we start with 1, and the last digit is twice as many as the previous number, so the equal number is 2. To figure out the number of the seventh day, we simply need to use the first number of 1 and multiply the equal number of 2 by 7 minus 1 power. ”

"2 to the 6th power, for sixty-four,"

"As for summing, it's simpler. In equal multiples, only the last digit of the number is used, and the first digit is subtracted, which is the sum of all the previous numbers. ”

"Take the first seven days as an example, if we want to calculate the sum of the first seven days, we don't need to add them one by one, we just need to come up with the number of the eighth day, which is the seventh power of 2, to get 128. Subtract the first number 1 from this number to get the sum of the previous seven days, which is 127. ”

"By analogy, to solve the problem just now, you only need to calculate the number of 366 days, minus 1, which is the sum of 365 days."

"Of course, I went a little too far with the question. The power of 2 of 366 is huge, and has exceeded 100 million trillions. ”

"But 2 to the power of 366 can still be calculated, we just need to disassemble 366 into ......"

Zong Xiu didn't understand the firewood Lingwu and others, so he directly simplified the formula of [equal proportional summing] thoroughly, and even briefly described the theory of opening the square in a few sentences.

Rao is like this, and when Zong Xiu finished speaking, it was dark, and lanterns were lit in the pavilion.

However, whether it was Kong Yingda, or Fang Yiai, Wei Shuyu, Du Gou and other six small princes, and even their scholars, they were all fascinated by it.

As the so-called one-size-fits-all approach, things in arithmetic are actually very simple, as long as you understand the rules, any problem can be solved.

Zong Xiu finished talking about 'Arabic numerals', 'simplified [equal proportional summing] formulas", and 'addition, subtraction, multiplication and division in later generations' one by one, and he only felt that his mouth was dry.