My sister, whom I raised, has turned evil after faking her death for three years.

After taking a shower, Jiang Ran changed into a light pink bunny pajama set with two long ears hanging down from the hood, swaying as she walked.

Holding the book she had spent ages picking out in the bookstore, she walked to the sofa, sat down, and placed the book neatly on the coffee table. Then she turned her head, her big eyes sparkling as she looked at Su Qing, who was still standing at the bedroom door drying her hair, and patted the spot next to her.

Su Qing immediately stopped drying her hair.

She has excellent eyesight, so good that she can see the large print on the cover of the book, "Elementary School Math Olympiad Thinking Training - Grade 5," even from three meters away.

She recognized these words, she recognized each one individually, but the moment they appeared together under Jiang Ran's command, her brain automatically triggered a system alarm.

Jiang Ran patted the spot next to her again, this time a little faster than before, her dark eyes filled with anticipation, "Sister, come quick, let's watch together."

The system issued a prompt in her mind: [Based on the current situation analysis, collaborative learning is beneficial for cultivating Jiang Ran's concentration and study habits, while also improving her social expression skills.]

[The system suggests that the host temporarily set aside their aversion to mathematics and participate in this interaction, as this will be beneficial to Jiang Ran's growth.]

"A little bit? You call my fear of math a little bit?!"

Su Qing asked the system in disbelief.

[Wording revision: It is suggested that the host let go of their strong aversion to mathematics.]

Su Qing took a deep breath, draped the towel over the back of the chair, and walked to the sofa.

Jiang Ran looked up at her, her eyes filled with such intense anticipation that they were almost overflowing.

Looking at her eyes, Su Qing swallowed the words "I'll go cut you some fruit, you can see for yourself" that were stuck in her throat.

I had no choice but to sit down.

Jiang Ran's lips immediately curled up. She moved closer to Su Qing, her shoulder brushing against her arm, and then opened the math Olympiad problem set, turning to the page with the bookmark.

My sister agreed, even though she clearly dislikes math!

Jiang Ran looked down at the question, and the corners of her mouth curled up a little higher.

Su Qing put on her Bluetooth earphones, randomly opened a playlist, and leaned back on the sofa to browse her phone.

She was afraid that the sound from her phone's speaker would disturb Jiang Ran while she was doing her homework, so she always turned the volume down to a level that she could just hear herself.

Several videos scrolled across the screen; she watched one and then swiped away. The music in her headphones changed to an older folk song, the guitar playing soothingly and gently.

About twenty minutes later, Su Qing suddenly felt that something was wrong.

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It's too quiet.

When Jiang Ran is doing her homework, she usually mutters to herself, and occasionally she will turn her head to ask her, "Sister, how do I do this?"

But today there was no sound at all, and even the eraser was being used very infrequently.

She took off one earphone and tilted her head to look over.

Jiang Ran was leaning on the coffee table, her left hand supporting her chin, and her right hand holding a pencil, writing something rapidly on a draft paper.

Her brow was slightly furrowed, but the corners of her mouth were upturned.

It wasn't the kind of expression that showed boredom because it was simple, but rather a focused concentration that only comes through when tackling a difficult problem.

She had already flipped to the second half of that fifth-grade math Olympiad problem set. The answers to the problems she had done earlier were marked with dense pencil marks, and most of the blank pages at the back were filled with scratch paper.

Su Qing took off her other earphone and turned to look at the problem Jiang Ran was working on.

"A cuboid has a length, width, and height that are three consecutive even numbers. Its volume is 960 cubic centimeters. Find the surface area of ​​this cuboid."

She stared at the question for a few seconds, then silently looked away.

Fifth grade.

cuboid.

Consecutive even numbers.

Volume 960.

Surface area.

She recognized each of the words individually, but when they were put together, her brain automatically entered a state of calm, almost like being in standby mode.

"System," she exclaimed inwardly, "is this really a fifth-grade question?"

[Yes, this is a typical fifth-grade math Olympiad problem, involving the calculation of the volume and surface area of ​​a cube, as well as the algebraic expression of consecutive even numbers. Judging from Jiang Ran's current progress, she will probably be able to—]

"Stop analyzing, I don't want to know the solution process."

Su Qing interrupted, "I just wanted to confirm, is it normal for a first-grader to be doing fifth-grade math olympiad problems?"

The system paused for a moment: [According to database statistics, the percentage of first-grade students who can independently complete fifth-grade math Olympiad problems is approximately 0.003%, which is a statistically extreme outlier. However, you already know that her talent rating is A+.]

Su Qing wound up the earphone cord and put it in her pocket, then reached out and gently poked Jiang Ran's arm with her index finger.

Jiang Ran looked up from her sea of ​​questions, blinked, and her face still held the focused expression she had while doing the questions, but when she met Su Qing's gaze, she immediately switched to a well-behaved smile.

"Why study so hard?"

Su Qing looked at her seriously, her tone slightly lecturing, "At your age, you should be playing carefree. Doesn't Cheng Xiaoyu always ask you to build sandcastles? And that obstacle course game, doesn't he talk about it all the time?"

The system issued a remarkably restrained notification in her mind: [Host, do you feel you're doing the right thing? Many parents would love for their children to be as hardworking as her. As her guardian, you should set a good example. According to relevant data analysis—]

Su Qing ignored what it said next.

Upon hearing this, Jiang Ran was taken aback for a moment, then smiled helplessly.

That smile was strange. Even though she was only seven years old, the way she looked at Su Qing was like she was looking at a little kid who needed to be coaxed.

"Sister, Cheng Xiaoyu's beach castle game is... I don't think it's as interesting as math problems."

Jiang Ran thought for a moment and swallowed back the words "very childish".

"And that puzzle game he mentioned, I saw his demonstration, it's just a little person jumping around on the screen, and every time he jumps into a pit he has to start over. He played for half an hour and still hadn't passed the level. I think it's not as interesting as doing a math problem."

She picked up the math olympiad problem set, flipped to the first few pages where she had already completed the problems, pointed to the answers that were neatly written in pencil, and looked up at Su Qing.

There was no boasting or pride in those bright black eyes, only a pure, heartfelt joy: "Sister, look, I feel so happy every time I solve a problem. When I don't know how to solve a problem, I don't understand it at first, but as I slowly figure it out, that moment when I suddenly understand it makes me incredibly happy, like playing a video game, but this one is even more fun!"

Su Qing looked at her and remained silent for about three seconds.

She thought back to her childhood... no, she didn't do any advanced math problems when she was a child.

When she was a child, her "challenge games" included climbing over walls without getting caught by security guards and having a few dollars left after a day of carrying bricks at a construction site to buy a bottle of soda.

For the first time, she realized that there were actually people in the world who found math problems more fun than games.

And this person is sitting right next to her now, wearing bunny pajamas, his eyes sparkling as he holds up a book of advanced math problems.

Su Qing leaned back on the sofa and let out a long sigh.

Sure enough, comparing yourself to others is a sure way to make yourself miserable.

She struggled with the chicken-and-rabbit problem for days, but this little guy, on the other hand, was already at the fifth-grade math olympiad level in first grade, saying it was "like a level-based game."

However, Su Qing then thought again, this is her younger sister!

The child she raised! A genius! She's so proud of him!

Su Qing's lips immediately curled up uncontrollably, and she couldn't suppress it no matter how hard she tried.

[Host...] The system's voice interjected at the opportune moment, [It's necessary to remind you that we just detected an extremely rapid shift in your emotions from 'feeling inferior' to 'smug pride'.]

[For reference, Jiang Ran's learning talent rating is A+, while yours is D. Jiang Ran's mathematical talent is her own ability, not a result of your educational efforts.]

"Shut up."

"OK……"