"You three are slowly calculating. By luck, I got one step ahead." Li Mengxi said with a smile on his face, modestly.

How could Liu Guanzhang calculate with his bare hands that his proficiency could be compared to that of Li Mengxi, who had gone through exam-oriented education?

Liu Bei smiled, shook his head, and continued to calculate.

It can be said that the problem is not complicated, but the number is so large that it is quite difficult to calculate.

Li Mengxi knew how to calculate vertically and horizontally. He was curious about how Liu Guanzhang and others calculated.

So Li Mengxi got up and walked over to see the calculations of Liu, Guan, and Zhang.

Walking behind Guan Yu, there was not a single word left on Guan Yu's paper except for the question stem and the answer to the first question.

Moreover, judging from the way Guan Yu pinched his knuckles and frowned in thought, he was obviously doing mental calculations.

Li Mengxi exclaimed, the numbers are so big and messy, how can he have such a strong mental arithmetic ability?

Guan Yu was very involved, and when Li Mengxi walked up behind him, Guan Yu didn't even notice.

Moreover, because Guan Yu's paper was clean, Li Mengxi's wish to explore the arithmetic methods of the late Han Dynasty was also in vain.

Another person changed and walked behind Zhang Fei. Li Mengxi saw that Zhang Fei had already finished calculating the addition and subtraction.

At this moment, Zhang Fei also finished the addition and subtraction problems and was doing the multiplication.

On the paper in front of Zhang Fei, Li Mengxi was surprised to find that Zhang Fei had drawn some criss-crossing long and short horizontal lines with unknown meanings. At the intersection of the counting horizontal lines, he counted and added, and wrote down the numbers one by one.

Although Li Mengxi couldn't understand it, he vaguely realized that the intersection of the horizontal and vertical lines drawn by Zhang Fei should be the product of each digit.

This method of drawing lines and calculating products was somewhat refreshing to Li Mengxi.

Li Mengxi watched for a long time and couldn't quite understand how Zhang Fei calculated.

This is very different from vertical calculation.

Turning to Liu Bei again, Liu Bei saw Li Mengxi coming and shook his head in confusion at Li Mengxi.

Liu Bei was not very good at calculations. Calculating such a large number made Liu Bei dizzy and he could barely finish the first question.

A long time passed, ten minutes or more.

Among the three Liu, Guan, and Zhang, Zhang Fei was the first to solve the problem.

Involving the four operations of addition, subtraction, multiplication and division, Li Mengxi designed the numbers to be too complicated and the amount of calculation was a bit large.

Zhang Fei finished all three questions.

Guan Yu asked two questions, and the last question was about division. Seeing that his third brother had already finished the calculation, Guan Yu decided not to do it at all.

As for Liu Bei, he forgot about the first question and stopped immediately.

Finally, Li Mengxi and the other three people answered the questions.

Zhang Fei made a mistake in his last question, and the division method was wrong.

"How could I be wrong!" Zhang Fei stared, "I said you were wrong!"

Li Mengxi opened his mouth, looked at his answer again, and said to himself, "It's impossible. I checked it twice."

"I'm sure it's not someone who is wrong, it's you, General Three, who are wrong!" Li Mengxi raised his head and faced Zhang Fei without flinching.

Upon seeing this, Liu Bei comforted the two of them, "Okay Yide, let's put aside whether the last number is right or wrong. Are the first two numbers the same for you two?" Liu Bei asked.

"Same." Li Mengxi said.

Hearing this, Liu Bei nodded and smiled, "That's it, Xi'er and Yide are both correct in the first two numbers!"

"But Yide, Ren Xi'er can calculate much faster than you!" Liu Bei looked at Li Mengxi with brilliant eyes.

Zhang Fei thought about it, that's right. Xiao Meng didn't have to wait long to figure it out.

Liu Guan and Zhang Sanying were convinced.

Li Mengxi looked serious and said to the three of them, "I will teach the three of them how to count."

After saying that, he bowed his hands to the three of them.

Liu Guanzhang looked solemn and returned the gift. This made Li Mengxi stunned for a moment. The expressions of Liu Guan and Zhang seemed a little too serious.

"I use vertical arithmetic for my hand calculations. I look at three digits, but I don't seem to know how to do it."

As he spoke, Li Mengxi took out a new piece of paper.

After thinking about it for a while, Li Mengxi thought that it would be better to start simple.

"Let's take a look at the three figures." Li Mengxi wrote a formula, written in numbers, 10-9=

Liu Guanzhang came over.

Li Mengxi earnestly imparted his knowledge without hesitation.

"Xuan Degong, do you recognize this number?" Li Mengxi pointed to the number "10".

"I know!" Liu Bei nodded.

"This is 10, this is 9."

"A dash in the middle means minus."

"The question is, what is the result of subtracting nine from ten?"

"One." Guan Yu answered without hesitation.

"Yes! This question is simple. Next, I will teach you how to calculate the vertical expression." After saying this, Li Mengxi wanted to laugh a little.

How do you feel like you are teaching children?

Of these three children, Zhang Fei is as strong as a bear and has a snake spear that can stab people like piercing a candied haws. Guan Yu is also as strong as an ox and has a big knife that can cut people like cutting vegetables. Liu Bei is a bit weaker, but he is also very powerful.

, a pair of long swords, slashing left and right, all in a mess.

These three kids are extremely talented.

Listed vertically.

The first line is 10.

In the second line, there is a single 9.

Li Mengxi pointed out the key.

"First, digital alignment. What is digital alignment? Hundreds and millions, one digit to one digit."

Li Mengxi pointed to the ones digit of 10, 0, and the minuend 9, and drew them vertically to indicate that they were correct.

"Then, it's just the ones minus the ones."

"Which number is the ones digit of 10?" Li Mengxi raised his head and asked.

Liu Bei frowned, "I don't know."

"Yes, 0.0 minus 9 is naturally not enough. What should we do?

You might as well go forward and borrow one, and borrow one for ten."

"Ten minus nine, you get one."

"Every person gets one."

"On the tenth place, because one was borrowed, one is gone."

"Do you understand?" Li Mengxi raised his head and asked.

Seeing Liu, Guan, and Zhang looking at each other, they looked confused.

Ten minus nine does not require much thought to know that the result is one, but Li Mengxi said that the numbers are correct, and one can be used as ten. This is an angle that the three of them have never thought of, and it is a little difficult to accept it for a while.

This seemingly simple question is designed with rigorous mathematical logic.

I found that using the example of ten minus nine was not very good. Li Mengxi scratched his head. The number in the tens place was no longer subtracted from one, and he could not clearly see the changes in the high position after borrowing one from the high position.

Li Mengxi put his only educational talent into full play. He then thought about a better example.

"Then change the question, let's subtract 17 from 86." Li Mengxi said.

"As mentioned before, the numbers should be aligned, one against one, ten against ten."

"Then, let's take a look." Li Mengxi pointed to the 6 in the minuend's digit and the 7 in the minuend's digit, pointing up and down.

"Six is ​​smaller than seven, so it's not enough to reduce. Is that so?"

Liu, Guan, and Zhang nodded, understanding this.

"What if it's not enough? If you go up to ten, borrow ten."

"Sixteen minus nine, what's the result? Seven."

So, Li Mengxi wrote a 7 under the vertical horizontal line.

"Look at the tens digit again. The tens digit is originally eight. I borrowed one. How many are left? Are there seven left?"

"Seven minus the next one, how much do you get?"

"Six?"

"So, 86 minus 17, we get, 69."
Chapter completed!