Operation Bernhard was a currency war in which a large number of counterfeit British pounds were counterfeited in an attempt to destroy the British economic system.
After Operation Bernhard, the world's first pound sterling with an anti-counterfeiting identification mark appeared, um, with a metal wire added to the original.
Looking at the six pounds in his hand, Yu Hua looked up to the sky and sighed, feeling very melancholy. He felt that he had dragged down the average wealth of the students of Peking No. 4 Middle School.
Emotionally, the poorest person in the school is either someone else or himself.
Look, for just six pounds, you can sell a light bulb in the school, giving it a taste of international trade.
Today we know what it means to be from a poor family.
After sorting out his slightly melancholy mood, Yu Hua put away the two precious pound notes. Yu Hua's mind turned and he silently pondered about the sales of portable lighting sources. After some research, he made a decision: "Deliver the party first in the first week." The three units of Jade are officially on sale to the outside world. Pre-orders are accepted. Five units will be delivered in the second week. For the time being, that’s it, just read a book.”
Memorizing the basic information from Zhang Wen in the literature class, the original plan remains unchanged and the hunger marketing strategy is maintained. Now Yu Hua's brain is like a high-performance mobile biological computer. There is no need to use paper and pen to record this information. It is very safe. , don’t worry about leakage.
Now, read a book.
Entering the library and going up to the second floor, it was still the same place, but Lin Wan was not there today. Yu Hua glanced at the empty place and felt a little uncomfortable. He noticed his own psychological changes and couldn't help but smile.
Sure enough, habits have become natural. I am used to the feeling of greeting Mr. Lin Wan every day. Today, he suddenly disappeared. It’s strange that I can’t adapt.
Shaking his head slightly, Yu Hua walked into the bookshelf along the narrow corridor. According to his memory, he went to the place where he borrowed the books before. He found two high school mathematics books. One was called "The Charm of Mathematics" and was a mathematics book published by his old friend Princeton. The readings, which tend to be basic and popular science, tell the story of the development and origin of mathematics, and why the Elements of Geometry still have unparalleled charm to this day.
"What is a Derivative" is a mathematics book written by Hardy, a professor of mathematics at the University of Cambridge. Most of it involves relevant knowledge at the high school level, and a small part touches calculus. It is biased toward professional knowledge and involves a small amount of advanced mathematics content.
Yu Hua sat down quietly and flipped through the first book The Charm of Mathematics. The article contained more words than mathematical formulas. It started with the origin of mathematics and mainly talked about the development process of mathematics in the West.
The book states that there are four periods in the history of the development of mathematics. The first period is called the formation period of mathematics. The earliest mathematics was formed in the first century BC and was mainly composed of arithmetic and geometry.
However, during this period, arithmetic had not yet been separated from geometry and formed a separate branch. Most mathematics involved understanding natural numbers and simple addition and subtraction operations.
The second period is called the period of elementary mathematics, also known as the period of constant mathematics. The time span is from the sixth century BC to the beginning of the seventeenth century AD. During this period, mathematics developed by leaps and bounds, covering arithmetic, geometry, algebra and other fields. , it is worth mentioning that all mathematical content born during this period is basically taught at the middle school level, including rational numbers, equations, real numbers, parallel lines, inequalities, etc.
During this period, Princeton's book also called it "dormant mathematics".
The third period is the period of variable mathematics, which spans from the beginning of the 17th century to the end of the 19th century. The emergence of French mathematicians Descartes and Fermat single-handedly created analytic geometry, which brought the development of mathematics to a whole new level. Then, As the 'Messenger of God' Isaac Newton and Leibniz, known as the 'Aristotle of the seventeenth century', fought against each other, the most important foundation in the history of mathematical development, calculus, was born.
Calculus in the early stages triggered the second mathematical crisis in the history of mathematics. Fortunately, with the crazy remedies of a series of famous historical figures, the mathematical crisis was resolved, and calculus, which had been wandering for more than a hundred years, finally became stable. .
The emergence of calculus has brought the mathematical development of human civilization to an unprecedented height, simplifying, stylizing, and formulating a series of mathematical problems, making it possible for the first time for mathematics to continuously search for and obtain abstract and identical answers from different fields. essence, and then generalize these essential changes. At this time, mathematics begins to show its own charm.
This Princeton book calls it 'the process of transforming mathematics into a mathematical weapon'.
With calculus, there are so many things that can be done.
Modern science separated from philosophy cannot do without the help of mathematics. Galileo, the father of modern mathematics, had two core concepts: first, to use mathematics to quantitatively describe science; second, to use experiments to verify science.
This is the role of mathematics. Mathematics has begun to become a logical weapon at an abstract level, helping human civilization accelerate its understanding of the nature of the world.
In the 19th century, also known as the period of contemporary mathematics, the development of mathematics began with set theory. Algebra, geometry, and analysis continued to undergo profound changes. Dynamic systems consisted of topological dynamic systems, and functionals composed of Hilbert spaces. Analysis, calculus perfecting rigor by Cauchy and Lebesgue integrals.
Princeton calls it a "bright pearl of mathematics". The book also talks about Goldbach's conjecture, the four-color conjecture and Fermat's conjecture. If these three major conjectures that have troubled the mathematical world for nearly a hundred years can be solved, the future Mathematics will definitely be able to shine and flourish even more.
"As expected of Princeton, this book spans thousands of years of history, from the origin to the present. It is compact and fast, making readers instantly interested in learning mathematics." Yu Hua finished reading "The Charm of Mathematics" and put it down gently. Closing his eyes, all the contents in the book came to mind, and then he seemed to have returned to those days when mathematics was developed, and he couldn't help but feel a sense of yearning in his heart.
Mathematics research seems useless, but in fact, it affects every aspect of life, from eating as small as possible to battleship manufacturing and cannons. Mathematics is not needed as a basis for building anywhere.
With the climax in the history of mathematics and the establishment of calculus, mathematics has completely become the basis of all natural sciences.
interesting.
Really interesting.
However, this Princeton book that had been hidden in the school library for a long time made Yu Hua see something different.
That's the Goldbach conjecture at the end.
Let’s not worry about the four-color theorem and Fermat’s last theorem for the time being. Goldbach’s conjecture, the most familiar and famous to Chinese people, is the one worth paying attention to.
Because the mathematical master who originally proved Goldbach's conjecture was called Chen Jingrun, who proved '1+2' in 1966.
It is clearly recorded in "The Charm of Mathematics" that the current Goldbach conjecture has only been deduced to '5 + 7', '4 + 9', '3 + 15' and '2 + 366', by Italian female mathematician Rei West Proof, published one month ago.
emmm, a very interesting thing lies in front of Yu Hua.
