When Li Mengxi gave the simple vertical algorithm to Liu, Guan, and Zhang clearly step by step, he asked another question.

Liu, Guan, and Zhang frowned and began to count unfamiliarly.

Li Mengxi was like an old gentleman, walking around the stone table with his hands behind his back.

Turning to Zhang Fei, Li Mengxi pointed over, "Third General, where do you want to borrow one?"

Zhang Fei raised his head, "Can't I remember?" Zhang Fei stared.

Zhang Fei's eyes are big, and when he opens them normally, he looks like he's staring.

"That won't work." Li Mengxi shook his head and stopped firmly, "If you want to borrow one from the front seat, you have to click one point."

Zhang Fei refused, twisted his neck and looked up at Li Mengxi, "I can remember it!" He said every word.

Zhang Fei is stubborn and fights for the sake of leverage.

"Even if you can remember it, you won't be able to remember it!" Li Mengxi didn't like Zhang Fei, so he stood next to him and watched him dotting the borrowed bit.

What can I remember? This is just a mathematical calculation of two numbers. After a while, I advanced to the calculation of a bunch of numbers. I borrowed one here and borrowed one there. If I didn't mark it, I would make a mistake soon.

Moreover, an important significance of written calculation is that it is more accurate than oral calculation.

Generally, simple problems that can be solved verbally can be solved directly.

If you are not sure about large numbers, you are afraid of making mistakes, so use pen to calculate.

Since we use a pen to calculate, the purpose is to make the calculation as accurate as possible.

This is good, for precise calculation, you have added an error-prone memorization process.

What are you picturing?

Turning to Guan Yu's side again, Li Mengxi glanced at the several vertical postures in front of Guan Yu.

"Here." Li Mengxi stretched out his hand and pointed to the left of the vertical position, "Draw a minus sign, which means subtraction."

Guan Yu then added a minus sign.

It needs to be standardized, and I'll have to learn addition later.

There is no need to add or minus signs to distinguish. What should I do if I make a mistake?

Next, we come to Liu Xuande's place.

Liu Bei took the initiative to move the paper to Li Mengxi and asked "Sir" to review it.

Liu Bei's attitude towards learning was serious.

Li Mengxi took a look at it and found that there was nothing serious wrong with it.

"Numbers, align them correctly, don't go too far." Li Mengxi said.

After another period of time, Li Mengxi checked the papers of the three people.

There are five vertical poses for each of the three, which are not very difficult and are all within two digits.

After checking, everything is fine and nothing is wrong.

However, from Zhang Fei's question paper, Li Mengxi saw that when Zhang Fei calculated vertically, he was missing the process of using small dots to lend. This made Li Mengxi confused. Zhang Fei calculated at the bottom or vertically.

Counted one by one.

The first round is over.

Further down, Li Mengxi tilted his head and thought for a long time.

Liu, Guan, and Zhang all stared at him.

There are vertical questions with increased difficulty.

First of all, Li Mengxi did not help them list the vertical equations directly. Instead, he only gave them the horizontal equations and asked them to list them themselves.

Then, the number got bigger, reaching one hundred thousand digits.

This is not the end, there are still multi-digit operations.

In other words, if it's more than a hundred thousand, reduce it by a few thousand, then tens of thousands, then reduce it by a few hundred, and so on.

The difficulty suddenly increased.

There were still three questions per person. After Li Mengxi finished listing the equations, he gave them to Liu, Guan, and Zhang.

As the night progressed, Li Mengxi suddenly remembered, where is Xiao Brick?

Taking a quick look, Xiao Bian lay down on the edge of the pavilion and fell asleep at some point.

Afraid that his brother would catch cold, Li Mengxi took off his coat and went over to cover and tuck his brother.

Liu Bei saw it and said, "Xi'er, why don't you go back first? We'll talk about it tomorrow." Liu Bei felt a little embarrassed.

"No problem." Li Mengxi smiled back.

In June, the days are hot and the nights are not that cool.

Although the calculation questions in the second round are still addition, the difficulty increases sharply.

Li Mengxi looked around and found that Liu, Guan, and Zhang calculated much slower than the first time.

The three of them had to convert the horizontal form into the vertical form themselves before they could do the math.

The largest number is here with Zhang Fei.

As he watched, Zhang Fei got the digits in the middle wrong carelessly, and reminded him carefully. After hesitating for a moment, he decided to forget it. He would wait for him to hand in the paper later, and then point out where he was wrong to give him an impression.

Repeated addition and subtraction of multiple numbers in vertical form, the process is actually repeated, two numbers are calculated, the calculation results of the first two numbers are calculated again with the third number, and so on.

At this point, it is highlighted why it is necessary to draw a minus sign or a plus sign to the left of the vertical form.

With the distinction, it is clear at a glance.

After another few minutes or ten minutes, Liu Guanzhang finished answering the questions.

To make corrections, Li Mengxi naturally had to count the numbers again.

After doing some calculations, I found that there were many errors and omissions.

"Third General, you were wrong first. Do you know where you made the mistake?"

"How could it be wrong?" Zhang Fei refused to admit that he was wrong.

"Here!" Li Mengxi leaned forward, pointed across the table, and pointed at Zhang Fei's first vertical pose.

"You are right or wrong in the middle thousand, but you are completely wrong in the rest."

Zhang Fei still wanted to refute, but he opened his eyes wide and lowered his head to scan the paper. Sure enough, he was right or wrong in the middle.

At this time, Zhang Fei couldn't refute and smiled awkwardly.

In this way, simple additions were performed first, and then complex additions were performed. First, Liu, Guan, and Zhang were helped to perform the vertical postures, and then Liu, Guan, and Zhang were asked to perform the vertical postures themselves.

The practice process of addition and subtraction was completed four or five times before Liu, Guan, and Zhang mastered it.

After that, more difficult multiplication and division.

Still following the simplest, gradually more complex, multiplication and division of multiple numbers.

After everything was taught, Li Mengxi felt sleepy and yawned frequently.

Outside, everything was quiet.

"I'll go back first. I'll teach the three of you tomorrow."

Li Mengxi said goodbye, and then Liu Bei helped Li Mengxi carry Xiao Brick back to the bedroom.

Li Mengxi couldn't sleep anymore, so he fell asleep on the bed.

Under the pavilion, the night is deep and the moon is in the sky.

After refilling the lampstand three or four times, the fire gradually dimmed again.

Liu, Guan, and Zhang sat upright, looking at the strange numbers on the paper in front of them, as well as various symbols for addition, subtraction, multipliers, and operations.

This is the Guigushen algorithm.

Li Mengxi Sihao did not keep it to himself, but actually took out everything he had learned.

With a hint of gratitude to Li Mengxi, Liu, Guan, and Zhang carefully reviewed their knowledge.

Finally, Zhang Fei looked at the earliest question, which was the question of "999,900 soldiers."

At that time, Li Mengxi said that his calculation was wrong. Zhang Fei looked at his answer and thought for a moment.

"I'm going to get the calculation chips!"

The number is so large that it is difficult to calculate without counting chips.

Calculator is a tool used to assist calculations in the Han Dynasty. It was invented before the Spring and Autumn Period and the Warring States Period, or even earlier.

Most of them are short sticks made of wood or bone.

Zhang Fei took a handful of counters and placed the long and short counters on the stone table, placing a few vertically and a few horizontally.

I don’t know how to calculate it. Anyway, Liu Bei can’t understand it.

Zhang Fei's family was rich and his education was better than that of Liu Bei, so Zhang Fei knew how to use a more complicated tool called calculation.

Wait for Zhang Fei to do the math several times.

The final calculation result was exactly the same as what Li Mengxi calculated with a pen at that time.

Zhang Fei didn't believe in evil, so he threw away his calculations, took a pen and paper and followed the method taught by Li Mengxi, and calculated the vertical formulas from beginning to end, multiplied and divided the vertical formulas again.

Calculating it in one go is faster than calculating with chips.

The result is paired with the correct result and is still exactly the same.
Chapter completed!