Chapter Ten: Astonishment

"Tongtong, your father and I are heading home now!"

Leaving her child at her mother's house, Mrs. Jin had no worries. Her daughter had grown up here since she was little; she was as familiar with this place as her own home, perhaps even more pampered here.

Tongtong had worked hard this month; it was only fitting she relaxed a bit at her grandfather's.

Wu Tong waved goodbye to her parents. She would stay at her grandmother’s for a couple of days, and if she wanted to go home, it was just a half-hour drive. There was nothing to be sentimental about.

Once Mr. and Mrs. Jin Yu had left, Jin Yongning directed his son to help Wu Tong carry her study materials upstairs, then cheerfully called his eldest granddaughter for watermelon. A watermelon small enough to fit into both hands, the top cut off, served with a little spoon—Wu Tong was spoiled and cherished in the Jin household.

After the watermelon, her aunt took Wu Tong to try on the new clothes she had bought her.

Xu Meifeng had an excellent eye and sense of style; the clothes she picked suited Wu Tong’s age perfectly—soft yellow, willow green, cherry blossom pink—all bright, youthful colors.

In Wu Tong’s memories of the future, she hadn’t worn such delicate colors for many years. After entering the workforce, her wardrobe was dominated by white, gray, black, and blue. Revisiting these vibrant shades of youth, Wu Tong smiled, realizing she was still young—why shouldn’t she wear whatever color she liked? She would cherish this youthful time.

Looping her arm through her aunt’s, Wu Tong gave her a thumbs-up in heartfelt thanks, making Xu Meifeng beam with joy as she hugged Wu Tong. Raising a daughter was certainly delightful—no matter how she dressed, she looked wonderful!

Her own son, well, when he was little, he was barely presentable; now he was impossibly rough! She only bought him new clothes at the change of season, from the same dependable shop—a few sets for rotation, all similar in style, practical and simple, leaving her no room to show her taste. Frankly, her husband dressed better than her son.

After spending a pleasant afternoon with her family, Wu Tong sat again at the desk—it was already four o'clock.

From Jin Xin’s bookshelf, she took out a workbook for second-year high school math. She only read the questions, covering up Jin Xin’s answers, and worked through them on scratch paper. If there were problems Jin Xin hadn’t done, she filled in the answers herself.

Could it be said they truly were siblings? Their study habits were identical—the main shortcoming being a tendency to doze off.

“Tongtong, are you getting serious now?” Jin Xin, following his mother’s orders, came upstairs to call Wu Tong for dinner. Opening the door, he saw Wu Tong working steadily through the problems, not just pretending for show. He couldn’t help but ask in a more cautious tone—was she really taking it seriously?

He had hurried home for dinner, needing to return to school for evening study.

The family meal schedule now revolved around Jin Xin’s timetable. Dinner started when Jin Xin walked in, punctual to the minute.

“Of course. When have I ever joked about this?” Wu Tong replied.

“…Thus, quadrilateral EFGH is a parallelogram.”

Wu Tong finished the geometric proof, raising her brows and nodding seriously.

“My little sister is better than her brother!” Jin Xin gave her a thumbs-up, genuinely sensing Wu Tong's determination.

If she decided to focus, she really meant business.

It was only when he entered his final year that he learned to discipline himself for the college entrance exam. With more and more people going to college these days, he needed at least a degree to be able to hold his head high, right?

It would also give him more confidence to back up his sister.

“Here, your big brother supports you with action!” Jin Xin pulled out, from his backpack, the math textbooks from the fifth volume of the required curriculum onwards.

At noon, he’d seen Wu Tong previewing second-year math. No matter the reason, since she was building the foundation, as her brother, he had to help her prepare thoroughly. So after school, he gathered all the math textbooks from second year onward and brought them home for Wu Tong.

“Don’t you need these for your own revision?” Wu Tong didn’t want to disrupt Jin Xin’s study schedule. Every moment in the final year was precious.

Jin Xin gave a cool little laugh and waved his hand. “Don’t worry, kiddo. We’re only at the start of our second round of review; I won’t need these for the next few days. Even if I did, Shi Tou and I can share one copy!”

The new textbooks for the semester would be issued at the start of school—at most, a few days away. What could it delay?

“Use them as you like. Don’t stand on ceremony with your brother!”

Wu Tong knew Shi Tou was her brother’s deskmate, Zhao Lei, his childhood friend—they were so close they could wear the same pair of pants.

“All right, then I’ll borrow these textbooks for two days,” Wu Tong nodded. One core volume, three electives, these were the last math textbooks for high school. If she worked quickly, she could return them to her brother by the morning of the day after next at the latest.

Jin Xin assumed Wu Tong’s “two days” was just a figure of speech, meaning the days before school started. He never imagined that in less than two days, Wu Tong would finish those textbooks thoroughly.

When Wu Tong returned the books to him early the next morning, catching him before his morning reading at school, saying she had finished them all, Jin Xin thought he must still be dreaming.

She must have just flipped through them, right?

“Tongtong, your brother really doesn’t need them yet!” Jin Xin scratched his head, still half-asleep and confused.

“I really finished studying them, and I added some summary notes for you. I hope they’ll be helpful. If you have any questions, you can come to me for tutoring anytime!” Wu Tong smiled brightly, almost as if she might accidentally provoke her brother—a little embarrassing!

“And here’s something in return—these are some practice exams you don’t have yet. I think the questions are good; take them and work through them. No need to thank me!” She had made two copies—her own she would finish in the next two days. Offering to help her brother with his studies was not an empty promise; she truly meant it.

These past two days, she had not only mastered all the key points from the second and third-year math textbooks, but had also spent a whole night integrating all the high school math concepts into a comprehensive knowledge tree.

Sets to sets, functions to functions, sequences to sequences—branches clearly laid out, the structure distinct. Every formula from high school math was now at Wu Tong’s fingertips, giving her a deeper understanding.

Her mathematical sword now honed to a razor’s edge, she was ready to tackle any problem high school math could throw at her.

Jin Xin, unable to believe it, flipped rapidly through the textbooks. In each of the four books, every chapter was marked with one or two sheets of densely written notes—analyses of the key points and derivations of the formulas.

Such an enormous amount of work—it was unimaginable!

He glanced through the chapter on trigonometry and geometry, the one he thought he knew best. There, in neat handwriting, were tightly reasoned analyses and thorough explanations—a teacher could hardly do better!

The result left Jin Xin utterly stunned. It was undeniable now—his little sister hadn’t exaggerated in the slightest; she had truly and thoroughly mastered the entire curriculum of second and third-year high school math in just two days!

Sixteen years, and only now did he realize he had a genius for a sister?

To master all of second and third-year high school math in two days—how could anyone live up to that?!