June 14, 2018. 7:00 a.m

Heli was about to go out when he was stopped by Hezhi, "Heli! You forgot to take your pen. He Li only remembered at this time, so he picked up the pen and said to Hezhi: "Thank you for the reminder, because today's exam made me too nervous, and I was a little scared." He Zhi said while sorting out He Li's clothes: "Don't be nervous, you have to be confident, I'll walk with you today, it just so happens that our high school is also going to take the exam." After speaking, Hezhi picked up his schoolbag and went out with Heli.

When Heli arrived at the school, he said goodbye to Hezhi, and Hezhi said, "I hope you can get a good score in mathematics, and make good use of the pen I gave you!"

Class 1 of Grade 8 of Shanghai Sunshine Experimental Middle School

"Ladies and gentlemen, today is the final exam of the second group of the experimental middle school, and everyone feels that they didn't sleep well yesterday, so they went to the bathroom to wash their faces and make themselves sober. The exam is coming up today, and you can spend your summer vacation with peace of mind after the exam. However, if you don't do well in the exam, don't think about it this summer! Review the questions carefully and think carefully. I believe that there is not a single subject that you will not be able to pass through! Well, in order not to waste everyone's time, now report the examination room and admission ticket number of all students. Zhang Haoran, Class 3 820140306; Huang Chengcheng, Class 2 8201421... As he listened, he took out the magic pen in his pencil case, and he thought, "How kind of spirit is this pen that can be called a magic pen by my sister?" No matter, let's try it first. As soon as he opened the cap and held the pen, the tip of the pen flashed for 5 seconds, instantly! All sorts of mathematical formulas appeared in front of him, and he was shocked.

"Heli!" Hurley was suddenly frightened, and the teacher stopped him and said, "What are you holding in your hand?"

"No, Mr. Yu, how is that possible?"

"You don't fart with me, aren't you holding a cheating artifact in your hand?"

At this time, Heli's heart panicked, and he hurriedly explained to the teacher: "Teacher, don't talk nonsense, what I am holding in my hand is an ordinary pen." Only then did the teacher calm down: "I hope you tell me the truth, don't lie to me, otherwise you will get zero points in all subjects!" By the way, just report your admission ticket number, 2 classes 820140209. “

Hurley thought to himself, "It's over, if the invigilator finds out, then I'll be cold, what can I do?"

The most terrible thing is to inspect the teacher.... Wait, this pen will glow for only five seconds, so just hide it for five seconds, and that's still fine!"

"Ding-woo!" The school's electric bell rang to signal that the students could begin to enter the exam room, and just as Hurley was about to leave, he was stopped by his tablemate

"Zhu Zhijun, what are you doing?"

"That's, Hurley,.... Lend me your pen to play with. Hearing this, Hurley thought, it seems that it is really not easy to use this pen, and he was suspected of cheating by the teacher a second ago; In the next second, he was going to be toyed with by other classmates.

"Heli, give it or not, if you don't give it, believe it or not, I will invite you to eat steamed buns'?" At this time, Heli's heart was even more panicked, "Don't worry, I won't break it." Heli reluctantly agreed: "Okay.... All right. ”

"Heli, why is this pen of yours so magical, it actually has a mathematical formula!" At this time, Heli scratched his head and said, "This is given to me by my sister."

"I want it too! What's your sister's name?"

"Hezhi, you can call her Sister Zhi, now a freshman in high school."