Who is Liu Hong?
A leading figure in the academic world, tied for first place with Cai Yong, actually said he wanted to take me as his disciple. It was like a huge, fragrant pie suddenly falling from the sky right in front of me...
Fei Qian instinctively opened his mouth, then quickly closed it. Hmm, this scene feels somewhat familiar. It's like something that happened in a leader's office in my past life—when a head from another department happened to come over for business, and you handled it smoothly. They praised your competence and casually asked if you wanted to join their team...
If you agreed, everyone would just laugh it off, and then you'd be left with nothing but awkward chuckles...
Moreover, this is the Han Dynasty, a period that places great emphasis on teacher-student relationships. The earlier the era, the more importance is placed on such connections. Unlike modern times, where everyone has countless teachers from elementary school to university—Chinese teachers, math teachers, not to mention those for sports, music, or substitute teachers—so for modern people, teachers are too numerous to feel particularly special. In contrast, in ancient times, a person might only have one or two teachers in their lifetime, which naturally leads to a different level of respect for teachers.
"Almost fell into a trap," Fei Qian thought to himself. "Liu Hong looks dignified, but I didn't expect him to dig such a big pit for me..."
So Fei Qian cupped his hands in respect and said, "Thank you for your kindness, Master Liu, but I already have a teacher."
Liu Hong hadn't actually intended to set a trap for Fei Qian. He was just a bit excited and spoke without thinking. But as soon as the words left his mouth, he regretted it. Poaching someone right in front of their current mentor, even if he and Cai Yong were old friends, was still awkward. Fortunately, Fei Qian didn't agree, otherwise it would have been really troublesome.
Seeing Fei Qian's response, Liu Hong decided to play along and act oblivious, "Oh, who is your teacher?"
At this point, Cai Yong coughed twice—alright, Liu Hong, stop pretending. I just told you that Fei Qian is my nominal disciple, and I called him here. So, who do you think his teacher is? You think Fei Qian is good? I think so too, so stop dreaming. Before Fei Qian could answer, Cai Yong said, "Ziyuan was recommended to me by an old friend, so it was fate that I took him as my disciple." This time, Cai Yong intentionally omitted two words, upgrading Fei Qian from a nominal disciple to a full disciple.
When no one was competing, it didn't seem like much, but with someone else interested, Cai Yong felt that Fei Qian was actually quite good. His looks, though not as handsome as mine, are still quite refined. His knowledge, though not as extensive as mine, managed to impress Liu Hong with some mathematical insights—this old guy who always brags about his mathematical prowess now sees my disciple surpassing him. What a great feeling...
Everyone has their little vanities, whether ancient or modern.
Suddenly, Liu Hong slapped his forehead and said to Cai Yong, "Oh dear, I almost forgot. I came to bid you farewell. I'll be leaving Luoyang soon!"
"Why? You just came back not long ago. What's going on?" Cai Yong was very surprised.
Liu Hong said, "I've been appointed as the Prefect of Shanyang Commandery. Here, I've even received the official seal." With that, he pulled out the prefect's seal from his robe and showed it to Cai Yong.
A commandery prefect is a high-ranking local official, and although Shanyang isn't a major commandery, it's still quite respectable. Cai Yong then felt relieved and asked, "When will you be leaving? I'll see you off."
"Alright, in a few days," Liu Hong agreed without hesitation. Then he pulled out a small square wooden box, slightly larger than a palm, from his robe and handed it to Cai Yong. "Here, take a look." His tone suggested he was showing off some rare treasure.
Cai Yong took the box, made of ebony and beautifully lacquered. He shook it slightly and heard something inside.
Under Liu Hong's guidance, Cai Yong opened the box to find it divided horizontally into three layers—the top layer was the smallest, the middle and bottom layers larger. Each layer was painted in black, white, and red to differentiate them. The box was also divided vertically into nine columns, creating ninety small compartments with the horizontal layers. In the black and red layers, each compartment contained corresponding colored wooden beads—nine black beads and thirty-six red beads. The white layer in the middle was empty.
"What is this?" Cai Yong frowned. Although he didn't know what the box was for, it felt strangely familiar, but he couldn't quite place it...
Liu Hong stroked his beard smugly, enjoying Cai Yong's puzzled expression—after all the effort I put into creating this ingenious device, how could you guess it so quickly?
Fei Qian, watching from the side, also felt that the design seemed familiar and was trying to guess what Liu Hong's device was for—but one thing was certain, it must be related to mathematics. Someone like Liu Hong wouldn't just show off a random toy.
As Cai Yong pondered, he casually picked up a black bead from the top layer and placed it in a compartment in the white area. He looked around but still couldn't figure it out. Then he took a red bead and placed it in the white compartment...
Suddenly, Fei Qian had an epiphany. Black beads, red beads, layered compartments, placed in the middle... This pattern reminded him of something. He blurted out, "An abacus!"
Liu Hong, who had been smugly stroking his beard, was so startled that he pulled out a couple of hairs. He turned to Fei Qian and asked, "How did you know?!"
"An abacus?" Cai Yong murmured, then quickly realized. It was just like the long counting rods turned into beads and placed in a box, forming a disk. "Haha, so it's just an abacus. I had already figured it out..."—of course, he had to save face, but inwardly he was impressed by Liu Hong's ingenuity.
Most people in the Han Dynasty still used counting rods for calculations. The "chou" in the ancient phrase "strategizing within a tent" refers to these counting rods.
Counting rods are essentially small sticks. Depending on personal preference, there are two modes of counting: horizontal and vertical. It sounds complicated, but it's just about whether the rod representing the number "one" is placed horizontally or vertically.
However, counting rods have inherent flaws, such as being inconvenient to carry, easy to lose, and prone to mixing up during calculations. Sometimes, if you stop midway to do something else, you might forget whether you were counting horizontally or vertically, forcing you to start over...
Liu Hong, being a master of mathematics, was acutely aware of these issues. After much deliberation, he invented this tool, simplifying the rods into beads. Red beads represent one, black beads represent five, and the white area is for calculations. Each vertical column represents a digit, and with nine columns, it can count up to the hundred millions, greatly satisfying the needs of calculation.
Today was the first time he showed the finished product to Cai Yong, hoping to impress him. But Cai Yong didn't recognize it, while Fei Qian, standing beside him, immediately saw through it. How could Liu Hong not be surprised?
*****
A/N: Liu Hong is later revered as the "Sage of Calculation," largely due to his invention of the abacus. Unfortunately, figures like him are rarely mentioned in the "Romance of the Three Kingdoms"... After all, it's just a novel...