Zheng Qian did not immediately take the engagement cancellation letter to the Wen family or the authorities.
After all, the cancellation required forty thousand taels. She had to be careful.
According to the currency conversion in Zheng Qian's original world, forty thousand taels was roughly equal to four million Interstellar Alliance credits.
Four million credits were enough to buy a beautiful estate on a somewhat remote planet.
How could she simply throw away such a huge sum?
Zheng Qian, who had grown up as an orphan, was not some extravagant rich second-generation heir.
She intended to extract as much of her betrothal money as possible from the Jing'an Marquis Manor—every bit she could recover mattered.
"With this cancellation letter, at least I have a backup plan," Zheng Qian thought.
She placed the letter into her storage space.
Holding her cat, she returned to Huining Courtyard. Madam Dai and the maids had already finished breakfast and gone back to their tasks.
The stewed beef and fresh milk prepared for the cat were sitting on the table.
Zheng Qian let Achou eat.
Whatever Zheng Qian gave him, Achou always ate enthusiastically.
She gently stroked his head.
"Achou, your mom has money again. What should I buy for you?"
Achou meowed.
Of course Zheng Qian couldn't understand cat language, but she still laughed and talked to him.
Just after Achou finished eating, Madam Dai and Xiuzhu entered carrying abacuses.
Zheng Qian had decided to teach her maids abacus calculation.
Whether they stayed with her or eventually married and left the household, knowing how to do accounting was a valuable skill.
Even professional accountants often refused to teach it to others.
The maids were all eager to learn—even Madam Dai didn't want to fall behind.
Zheng Qian divided them into pairs to study in shifts so household work wouldn't be delayed.
If Madam Dai and Xiuzhu studied in the morning, Hongluan and Caiyuan would come in the afternoon.
Each wooden abacus cost three taels of silver, all purchased by Zheng Qian.
"…When subtracting, borrow ten and compensate five," Zheng Qian explained. "Remember the abacus口诀 (calculation rhymes). Once you memorize them, it becomes very easy."
Xiuzhu and Madam Dai studied seriously.
After only three days, they had basically mastered it.
"I never understood how to use the sand table before," Xiuzhu said. "Madam Dai tried teaching me several times. But with the abacus, I learned immediately."
Madam Dai nodded.
"That's because the young mistress is talented."
"The abacus itself is impressive," Xiuzhu added. "But since the young mistress invented it, she's even more impressive."
Zheng Qian laughed.
"It's nothing special. Arithmetic itself is very simple," she said.
"With the help of the abacus, plus the multiplication table, accounting becomes easy."
"What is the multiplication table?" Madam Dai asked curiously.
Zheng Qian paused.
Her personal terminal database told her that the multiplication table had existed in ancient China since the Spring and Autumn / Warring States period.
"'Three times seven is twenty-one, nine times nine is eighty-one'—aren't those common sayings?" Zheng Qian asked.
"Yes," Madam Dai said.
"Isn't that the multiplication table?"
Madam Dai and Xiuzhu stared blankly.
Aside from those two phrases, they had never heard the rest.
Zheng Qian was confused.
She asked Madam Dai to investigate.
The result was surprising.
Most people did not know the multiplication table at all. Even those familiar with "nine times nine is eighty-one" didn't associate it with any calculation method.
The phrase "whatever, three-seven-twenty-one" existed only as slang meaning acting recklessly.
Zheng Qian thought for a moment.
"It must have existed before," she said. "Perhaps it was lost over time."
During the Warring States era, the world had been divided and constantly at war. Cultural knowledge could easily have been lost.
Or perhaps this world was not ancient China at all.
Maybe when her spacecraft exploded in space, she had been pulled through a wormhole into a parallel world.
"Well, if it doesn't exist, then I'll teach it to you."
She began teaching them the multiplication table, explaining how to use it for accounting.
Madam Dai was shocked after hearing it once.
"Young Mistress, this is a treasure! You shouldn't teach it casually—you must keep it secret!"
"What treasure? It's just arithmetic," Zheng Qian said. "Even children know it."
Madam Dai insisted she treat it like a family secret, passed only to descendants like certain medical clans.
Zheng Qian shook her head.
"If society progresses together, we can all benefit more. If knowledge is hidden away, society stagnates—and I'll be trapped here too."
Madam Dai didn't understand that reasoning.
"In any case, memorize it. It's easy—have it learned by tomorrow," Zheng Qian said with a smile.
The maids agreed immediately.
As they recited the multiplication table, the cat sat nearby quietly memorizing it too.
His green-and-gold heterochromatic eyes stayed fixed on Zheng Qian.
His heart softened strangely.
"How does she know everything?" Xiao Zhan wondered.
The mosquito coil formula she created had already been bought by Xiao Mingyu for a high price.
The abacus she invented had impressed many people—including Xiao Zhan.
And now she had introduced the multiplication table.
Xiao Zhan was a military general.
He rarely handled logistical administration, and calculating military rations had always given him headaches.
But with the multiplication table and abacus, even he could manage military supplies.
Supply officers would no longer be able to deceive him.
He had never known the Zheng family's eldest daughter to be so capable.
Or perhaps…
She wasn't truly Zheng Qian anymore.
When Zheng Chi touched her face earlier, Xiao Zhan had wanted to scratch him. But he understood—Zheng Chi had the same suspicion.
This woman was not the original Zheng Qian.
"No matter who you are," Xiao Zhan thought, "since I met you, you will always be Zheng Qian."
Meanwhile Zheng Qian tested the maids on their recitation.
Xiuzhu learned the fastest.
Madam Dai followed closely.
Caiyuan barely kept up.
Hongluan couldn't get it at all.
Watching her struggle to answer "What is four times six?" Zheng Qian burst out laughing.
"Forget it, this girl is slow. Let her learn gradually."
There were no final exams here anyway. Learning in one year or even ten years made no difference.
"Since you came last today, your punishment is to tell us an interesting piece of news," Zheng Qian said.
Hongluan brightened immediately.
"Young Mistress! I just heard that on West Street a new fabric shop opened. Third Madam and Concubine Zhou invested in it together."
Madam Dai froze.
She quickly interrupted.
"Don't talk nonsense. Go memorize your multiplication table."
Zheng Qian waved her hand.
"It's nothing surprising. They're just using my betrothal money to do business."
Concubine Zhou was Zheng Run's mother—the marquis's only concubine. She had no money of her own.
The real person behind her was the Marquis of Jing'an.
Third Madam already controlled many shops and had absorbed Zheng Qian's mother's dowry into the household assets long ago.
The family relied on her wealth, while she relied on controlling household power.
Now the Wen family's forty-thousand-tael betrothal gift had become new capital.
They would open a shop, falsify accounts showing losses, swallow Zheng Qian's money, then later inject new funds to "turn the business profitable."
The profits would belong to them—not Zheng Qian or the Wen family.
A perfect scheme.
"I suspected my betrothal money had been used already," Zheng Qian said calmly. "Now it's confirmed."
"Young Mistress, don't be sad," Madam Dai said.
Zheng Qian smiled.
"Why would I be sad? I just need to find an opportunity to get that money back."
Hongluan looked excited.
"How?"
Zheng Qian smiled slightly.
"Wait. Opportunities always appear."
Nearby, Xiao Zhan licked his paw thoughtfully.
He wondered whether he should sneak into the Marquis's courtyard tonight…
and dig out his eyeballs.