Having found the answer to the question, Song Ning'er walked away, humming a song and feeling smug.
Song Mu'er sat in the pavilion, arms crossed, her back towards Li Nuo, and her puckered little mouth could have hung an oil pot.
She was truly angry. Song Ning'er wouldn't play vine ball with Brother Li, instead she joined him in kicking shuttlecocks, offered him little cookies, and though he clearly knew she didn't get along with Song Ning'er, he still played with her behind her back. At such a young age, the little girl had already tasted the flavor of betrayal.
In actuality, even though Li Nuo favored Mumu more, he wouldn't hold a grudge against Ning'er for not letting him play ball last time. After all, it was just discussing a question, and Li Nuo didn't think there was anything to it.
However, witnessing the angry Song Mu'er, Li Nuo could only helplessly explain, "You two look exactly alike, I mistook her for you."
Mainly because Song Ning'er had been pretending to be her sister all along, and Li Nuo hadn't doubted it for a moment.
Who would have thought that a six-year-old girl's schemes could run so deep?
Finally, Song Mu'er turned around, glanced at Li Nuo, and asked softly, "Really?"
Li Nuo held out his palm and said, "If I'm lying, I'm a little dog."
To Song Mu'er, this was a serious oath. The smile returned to her face, and she ran over to Li Nuo's side, saying, "Alright, I'm not mad at you anymore. It's all Song Ning'er's fault..."
Li Nuo thought to himself how easy little girls were to placate, but Song Mu'er was seriously contemplating how to prevent such impersonations by Song Ning'er from happening again.
After some thought, her eyes lit up as she looked at Li Nuo and said, "Let's come up with a secret code that only the two of us know. Whoever can't give the secret code is Song Ning'er..."
Li Nuo could only agree to her proposal.
After discussing together, they decided on the code "one, two, three, four, five, let's go uphill to fight the tiger." Only someone who could respond correctly would be Song Mu'er, otherwise, it would be Song Ning'er.
Honestly, it was quite an effective way to differentiate between twins.
Although it was just explaining a question, and it didn't make a difference whether they distinguished themselves or not, Li Nuo didn't want to be confused.
Song Mu'er had come over to ask Li Nuo a question as well. He glanced at it and saw that it was exactly the same question as Song Ning'er's, which he had already explained once. Explaining it a second time, of course, was easy and familiar.
Song Jiaren looked at the problem on the paper and felt her headache starting again.
Those equations brought back painful memories from ten years ago.
She remembered that when she was learning mathematics, the hardest part had been to put chickens and rabbits in the same cage, what with this hemp, wheat, beans, the responses, millets – just the problem statement filled a page. Are kids supposed to learn such difficult mathematics today?
While explaining for the second time, with the foundation of the first, those examples from simple to complex came easily to Li Nuo.
The twin sisters deserved their name; not only did they look the same, but their comprehension abilities were very similar too. What Ning'er could understand, Mumu could as well. She calculated step by step and soon found the answer.
Song Mu'er looked at the result she had calculated and murmured in disbelief, "So this question is actually this simple..."
Even Song Jiaren's eyes showed a hint of surprise.
As Li Nuo was explaining to Mumu, she had been listening on the side, and as she did, she realized that this page full of complex mathematical problems didn't seem so difficult; not only did Mumu understand it, she did too...
After this realization, there was a hint of irritation in her heart.
If her mathematics tutor during her childhood had been Li Nuo instead of that old man, her mathematics wouldn't be so poor.
At that moment, an unfounded thought arose in Song Jiaren's heart.
If only she had met him earlier...
After explaining the problem, Li Nuo stood up and stretched his body.
A quintic set of equations might sound intimidating, but in reality, they involved only some of the most basic operational rules. With their current level of mathematics, they could master it well.
Of course, it was mainly because Li Nuo was there to guide them.
By using the method Li Nuo taught, he had Song Mu'er re-calculate the chicken-rabbit cage problem from yesterday. She quickly found the answer and clearly understood.
While Song Mu'er was reviewing the content she had just learned, Li Nuo returned to his room, coming out with a thick book in hand.
This book was titled "Calculus," encompassing all of Daxia's mathematics.
In Daxia, even in the whole world of that time, all mathematical problems were contained in this one book.
This reveals the level of mathematics of the era.
Modern mathematics after the recent era began to develop crazily, extending new branches from the foundations of ancient mathematics: number theory, algebra, geometry, topology, mathematical analysis... No single book could include all mathematical knowledge, let alone a hundred books or a thousand.
"Calculus" consisted of nine sections, known as "Nine Numbers," which were square field, Suzi, Decaying Division, Shao Guang, Commerce, Jun Shu, winning and losing, equations, and Pythagorean. Each section studies a type of similar problems.
For example, the "square field" section specializes in the calculation of field areas, providing formulas for various polygons, circles, bow shapes, as well as fraction operations and arithmetic rules.
"Commerce" was about volume calculation, providing formulas for various volumes, useful in the construction of city walls or digging trenches, to calculate earthwork and labor.
The "Jun Shu" section details how to fairly distribute taxation; to address the burden of corvée, and other sections each have their uses. In short, the mathematics of this era had a very strong purposefulness and almost corresponded with various real-life problems.
The chicken-rabbit cage problem from yesterday and today's grain problem belonged to the "equations" section in "Calculus."
However, "equations" here are not the same as the modern ones, which refer to mathematical expressions containing unknown values. In "Calculus," "equations" referred to modern systems of linear equations.
Li Nuo looked over the content for a while, and had a rough idea.
The content of "Calculus" included parts of middle school and high school mathematics from the future. Most of the problems could be solved with high school knowledge. To someone who had just undergone the college entrance exam, their level of mathematics was an overwhelming advantage over people of Daxia, although that might not be the case for college students…
Song Mu'er finally understood the problem posed by her teacher. Seeing that Li Nuo was absorbed in reading and not wanting to disturb him, she ran out to the courtyard and said to Song Jiaren, "Jiaren Sister, check if my kung fu has gotten better…"
Li Nuo was engrossed in his book when he suddenly heard sounds from nearby.
He turned his head to look and saw Song Mu'er practicing in the yard. With each swing of her small fists, a gust of wind followed, and when she struck a tree trunk as thick as the mouth of a bowl, the sturdy trunk shook violently. Li Nuo even felt the ground beneath him quiver.
He watched, dumbfounded.
Is this really a six-year-old child?
After all this time, her claim of wanting to protect him wasn't just idle talk...
She truly had the strength!
As Li Nuo was shocked by the great power contained within her small body, footsteps sounded from the entrance of the courtyard.
Two figures slowly entered.
The one behind, all smiles, was none other than Housekeeper Wu.
The one in front was a refined-looking middle-aged man.
The middle-aged man stood tall and straight, probably around 1.8 meters in height, with sharp facial features, clear-cut lines, and three long beards flowing from his chin. He walked with measured steps, exuding an indescribable charisma.
If one had to describe him with just one word,
It would be handsome.
Really damn handsome.
Having dealt with the Chang'an County Magistrate Pei Zhe in the past few days, who was somewhat handsome too, Li Nuo felt that Pei Zhe still had a somewhat sleazy vibe. This middle-aged man was on another level attractiveness-wise and completely eclipsed Pei Zhe in charisma.
Wouldn't he ensnare countless young women when he was in his thirties to forties with such charisma?
Housekeeper Wu, who usually bossed the servants around in Li Mansion, was now respectfully trailing behind the middle-aged man. His identity wasn't hard to guess.
Clearly, this graceful and handsome man was the current Minister of Justice, the master of Li Mansion, the father of the body Li Nuo now inhabited.
Li Nuo had been in this world for several days, and this was his first time meeting him.
Housekeeper Wu trotted over, smiling, and said, "Young Master, the Master has returned..."
In his previous life, Li Nuo lost his parents when he was very young and was raised by his grandmother. The concept of a father was somewhat alien to him, and now, facing this stranger for the first time, the word 'father' felt even more difficult to utter.
The middle-aged man paced to Li Nuo's side and asked softly, "Is your injury better?"
Li Nuo came to his senses, bowing his head, "At the birthday banquet the day before yesterday, the Old Lady awarded me an Agricultural School's Longevity Peach... I have fully recovered."
The middle-aged man then asked, "Can't remember anything from before?"
Li Nuo nodded and responded, "I can't remember a thing."
The middle-aged man said, "It's okay, if you can't remember, then don't worry about it. If you need anything, just tell Housekeeper Wu..."
After a brief exchange with Li Nuo and patting him on the shoulder, the middle-aged man turned and left.
Li Nuo could tell that this high-ranking official seemed not adept at communicating with his son.
Coincidentally, Li Nuo was not good at this either, and this kind of peaceful interaction between father and son actually made him feel more at ease.
As the middle-aged man left, he nodded slightly to Song Jiaren, who stood in the courtyard.
Song Mu'er, hiding behind Song Jiaren, seemed a bit scared, gripping her clothes tightly with both hands, only her head peeking out.
Li Nuo walked over and rubbed Song Mu'er's head, asking, "Are you very afraid of him?"
Facing people like Song Yu and the others, she had the courage to puff out her little chest to protect Li Nuo. It was surprising that the fearless Song Mu'er also had someone she feared.
Song Mu'er nodded and said, "They say Uncle Li is very formidable, and many, many people have died at his hands."
Li Nuo inquired, "Who said that?"
Song Mu'er replied, "Brother Yu and the others."
The Ministry of Justice was responsible for criminal cases, and in Daxia, the power of local government offices was limited. Sentences of exile and above, including capital punishment, had to be ratified by the Minister of Justice. So, in a way, it wasn't incorrect.
Li Nuo smiled and said, "He only kills the bad guys. Mumu is a good person, so you needn't be afraid."
"Of course I'm a good person, Ning'er is the bad one..."
Hearing what Li Nuo said, Song Mu'er finally relaxed and went back to tormenting that poor tree.
Song Jiaren looked at Li Nuo with a strange gaze, full of indescribable meaning. Li Nuo noticed her stare and touched his face, unsure, "Is there something dirty on my face?"
Song Jiaren shook her head, "No."
Li Nuo muttered softly, "If there's nothing, then why stare at me..."
Her gaze lingered again.
While walking towards Mumu, Li Nuo commented, "Stare if you want, a glance won't take a piece of flesh off me, it's no big deal..."