In any school, exams and studies are always the same items.

Hogwarts is no exception, no matter how much changes have taken place in the castle this semester, it is still a place to impart knowledge, and when the end of the semester approaches, it will not change to end with exams.

According to Pythagoras' theory that everything is numbered, everything has a wonderful relationship with numbers, so it is undoubtedly a clearer and simpler way to analyze mathematics before studying the world.

Although there is still a lot of controversy in the academic community on this point, it is undeniable that using mathematical thinking to sort out and find connections between things is indeed an extremely efficient and clever way to find out the connections between learning materials, time patterns and final exam questions.

Elena picked up the messy pile of worn-out parchment papers on the table, and carefully spread them out on the floor of the room in chronological order, arranging them in rows according to different subject categories.

These papers are all from the corridor next to the "Piano Room", in the Room of Requirement, opposite the tapestry of "Troll Stick Beats Silly Barnabas", a secret magical room that exists in Hogwarts Castle, and does not have a fixed form, but changes according to the needs of the person seeking help - whether it is a toilet, utility room, training room, love room, study, dining room, armory room......

For Elena, though, what she needed was not a special-purpose room, but a search for the final exam papers that Hogwarts students had hidden in the Room of Requirement, either intentionally or unintentionally.

Concealing and destroying final exam papers is a very common practice in any school.

After all, except for a very small number of top students, not every little wizard is willing to put his final exam papers in his suitcase at the end of the semester and take them home to share with his parents and siblings.

Using the constraints of "where to hide things/where to hide test papers", Elena accurately found all the papers she wanted from the garbage heap-like responsive room to test her conjecture.

"Sure enough, I knew it was ......"

Elena looked at the past papers on the ground and whispered.

According to the definition in the preface, there must be finite solutions for parallel maps of finite sets, and order-preserving maps on compatible complete lattices have sign-preserving properties, that is to say, the test questions that seem to be infinitely set will inevitably stretch with the timeline and converge with the knowledge points of the textbook of finite sets, that is, the phenomenon of repeated solutions.

Of course, the above is how the average Muggle knows and understands the world.

From the perspective of a wizard who does not learn (none) mathematics (learning), that is, wherever the professor draws the key points, it is the scope of the final exam, although it ...... This focus is usually about the same as the textbook in the hands of the young wizards.

Long before the time travel, Elena had done a lot of research and speculation about the Hogwarts education system.

A large part of this is that the wizarding world's textbooks in basic education are changing incredibly slowly, the most obvious example is in the original book "Harry Potter and the Half-Blood Prince", the textbook used by Harry Potter in Potions class in 1997 is exactly the same as the textbook used by Snape in Potions class in 1976.

Not only the title of the book, but even some of the basic errors and cumbersome ways have not been revised or rewritten in more than thirty years, which is simply unimaginable in the non-magical world at the same time.

In addition, both the "Standard Spells" series and the "Guide to Elementary Transfiguration" are all works left by wizards hundreds of years ago, and there has been no change over the years, compared to the "History of Magic" compiled by Elena's "grandmother", it is still a rare textbook with more diligent revisions.

Putting aside the problems that may result from the long-term use of the same set of textbooks in terms of the quality of education, for Hogwarts professors, the final exam questions at the end of each semester are also a headache.

You know, unlike those schools in the non-wizarding world, Hogwarts has a rather severe shortage of manpower in terms of educational resources, and each professor has to deal with at least 5-7 years of young wizards, which means that at least at the end of each semester, they have to spare at least the corresponding number of sets of questions.

"It's not easy, in the dormitory system of Hogwarts, you have to find a way to prevent cheating. ”

Elena looked back at last year's final exams and found that the content of each year's exam papers was different from the previous year, and it was clear that the Hogwarts professors were not lazy enough to use only one set of exam papers for the exam.

This did not surprise Elena.

After all, in Hogwarts, students of all grades live in the same dormitory according to their respective houses, and if the same set of questions is used every year, it is easy for the senior students to miss the questions at the end of the semester.

"There are seven grades at Hogwarts, and if you want to keep the lowest level of the question bank confidential, it means that there will be no duplication of final papers between students in the school, which means ......"

Elena muttered thoughtfully, crouching on the ground and carefully checking and sorting out the discarded test papers issued from the "garbage heap" according to the year, as we all know, the simplest of mathematical inductions is exhaustive.

"1990, 1989, 1988...... 1985, 1984, 1983...... That's it!"

Looking at the platonite test paper in front of her, Elena quickly stood up and looked at the test paper that had just been thrown into the "garbage heap" last year, and put the two test papers that were 8 years apart together.

From the first question to the last question, everything is exactly the same, and if the time is obscured, it will even make people think that this is the test paper that the same students answered, but whether it is the old or new paper, or the name of the student written at the top of the paper, it is unmistakable to verify Elena's conjecture again.

Most of the Hogwarts subjects are examined using a seven-year cycle, in other words, the exam system used by students who graduated last year is exactly the same as the one that young wizards who have just entered the school this year.

In this way, the seven school years at Hogwarts have formed a cycle like an Ouroboros.

Except for the special Defence Against the Dark Arts course, the professors in charge of the other major courses don't have to bother to come up with new exam questions every year, and they don't have to worry too much about the problem of the real exam questions being leaked in advance.

I took a piece of French crème brûlée and stuffed it into my mouth, feeling the crunchy caramel melt little by little on the tip of my tongue, and the delicate, creamy, but not too sweet pudding touched her teeth coldly, Elena squinted her eyes happily.

"Tsk, it's just that I didn't expect to accidentally turn to the black history of two 'acquaintances'......"

............

The Room of Requirement is located in the corner hallway on the eighth floor of Hogwarts Castle.

Adjacent to the principal's office, the Gryffindor common room, and the Ravenclaw common room, if nothing else, it should be the work of Rowena Ravenclaw, one of the founders, after all, Gryffindor is not such a careful person.

Perhaps because of the unique location of the "Room of Requirement", most of the students who will use this place are young wizards from Gryffindor House and Ravenclaw House, which is more in line with the personalities of the students of the two houses.

The reckless Gryffindor lion cub will always have some dangerous items that he will try to destroy and discard.

And the sensitive Ravenclaw girl will also have many secrets that she wants to hide secretly from being discovered.

And the two test papers in Elena's hand happen to be a Ravenclaw House and a Gryffindor House, and what is even more interesting is that the owners of these two Potions first-year final papers happen to be 'known' to her.

Bill Weasley, Aki Chang...... I didn't expect these two good students to fail exams sometimes. Hmm, what's even more interesting is that this time Ravenclaw vs. Gryffindor's cross-time confrontation, I didn't expect Gryffindor to win?"

For Qiu Zhang, Harry Potter's first girlfriend in the original book, and a second-year Ravenclaw student with Chinese ancestry, Elena is naturally no stranger, although in terms of personal feelings, she has never liked this Chinese senior sister very much.

It's not that Elena deliberately targeted Qiu Zhang, mainly when she learned that Qiu Zhang not only couldn't even speak Chinese, but also lived in the British wizarding world since she was a child, and her three views and personal habits were also alive and clear from an English wizard, and there were not too many Chinese elements except for blood, and the estrangement caused by the psychological gap of expectations disappointed.

But studying in the same school, there are still some memorable interactions between the two.

For example......

During the few Quidditch matches against Ravenclaw House during the school year, the Silver and White Devil soaring through the sky almost effortlessly brought the entire Ravenclaw team to tears, so much so that every time Elena passed by the Ravenclaw table in the next few weeks, the eyes of several senior girls turned red instantly.

Among them, Qiu Zhang, who is also in the position of the Seeker, can be said to be one of the few little wizards who cry the loudest.

Except for her own little wings, Elena has always been as ruthless as the autumn wind sweeping away the leaves for the cabbage outside, and in the face of this senior sister who has a Chinese identity but has no sense of familiarity everywhere, it is really difficult for her to have too much intimacy.

However, for Bill Weasley, Elena has a completely different attitude.

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Chapter 1!!!!