1. Interesting facts about calculators
Interesting facts about calculators 1. What are the simplest common sense about computers?
What does each key on the keyboard do? F1 Help F2 Rename F3 Search F4 Address F5 Refresh F6 Switch F10 Menu CTRL+A Select all CTRL+C Copy CTRL+X Cut CTRL+V Paste CTRL+Z Undo CTRL+O Open SHIFT+DELETE Permanently delete DELETE Delete ALT+ENTER Attribute ALT +F4 close CTRL+F4 close ALT+TAB switch ALT+ESC switch ALT+spacebar window menu CTRL+ESC start menu press CTRL while dragging an item to copy the selected item press CTRL+SHIFT while dragging an item to create a shortcut Press the SHIFT key when inserting the disc into the CD-ROM drive to prevent the disc from automatically playing Ctrl+1,2,3. Switch to 1, 2, and 3 from the left. Tags Ctrl+A Select all the contents of the current page Ctrl+C Copy the currently selected contents Ctrl+D Open the "Add Favorites" panel (add the current page to favorites) Ctrl+E Open or close the "Search" sidebar ( Various search engines are optional) Ctrl+F Open the "Find" panel Ctrl+G Open or close the "Simple Collection" panel Ctrl+H Open the "History" sidebar Ctrl+I Open the "Favorites" sidebar/other : Restore all vertically tiled or horizontally tiled or cascaded windows Ctrl+K Close all tabs except the current and locked tabs Ctrl+L Open the "Open" panel (Iter addresses or other files can be opened on the current page.) Ctrl+N creates a new blank window (can be changed, Maxthon Options → Label → New) Ctrl+O opens the "Open" panel (iter address or other files can be opened on the current page.) Ctrl+P opens the "Print" panel (can Print web pages, pictures, etc.
) Ctrl+Q Open the "Add to Filter List" panel (send the current page address to the filter list) Ctrl+R Refresh the current page Ctrl+S Open the "Save Web Page" panel (can save all the contents of the current page) Ctrl+T Tile all windows vertically Ctrl+V Paste the contents of the current clipboard Ctrl+W Close the current tab (window) Ctrl+X Cut the currently selected content (usually only used for text operations) Ctrl+Y Redo the previous action (usually only Used for text operations) Ctrl+Z Undo the previous action (generally only used for text operations) Ctrl+F4 Close the current tab (window) Ctrl+F5 Refresh the current page Ctrl+F6 Switch tabs forward according to the chronological order of the page opening (window) ) Ctrl+F11 Hide or show the menu bar Ctrl+Tab Switch tabs (windows) downwards in a small menu mode Ctrl+numeric keyboard'+' Enlarge the current page by 20% Ctrl+numeric keyboard'-' Reduce the current page by 20% Ctrl+numeric keyboard'* 'Restore the zoom of the current page to the original size Ctrl+Shift+numeric keyboard'+' Zoom in all pages by 20% Ctrl+Shift+numeric keyboard'-' Reduce all pages by 20% Ctrl+Shift+F Move the input focus to the search bar Ctrl+Shift+ G Close the "Simple Collection" panel Ctrl+Shift+H Open and activate the homepage you set Ctrl+Shift+W Close all tabs except locked tabs (window) Ctrl+Shift+Tab Switch up tabs in a small menu (window ) Ctrl+Shift+Enter Domain name auto-complete Alt+1 Save the current form Alt+2 Save as a universal form Alt+A Expand the favorites list Explorer END Display the bottom of the current window HOME Display the top of the current window winver---- -----Check Windows version winmsd---------System information wiaacmgr-------Scanner and Camera Wizard winchat--------XP comes with LAN chat wmimgmt.msc ----Open windows management architecture (WMI) wordpad--------wordpad wauucpl.cpl----automatically update wupdmgr--------windows update program write----- -----WordPad wscript--------windows script host settings wscui.cpl------Security Center
I admire the question raised by the poster. He wants to ask about computers. Maintenance issue or problem with computer operation?
2. Computer knowledge
Electronic Numerical Integrator Computer The first electronic computer was called ENIAC (short for Electronic Numerical Integrator Computer, the full English name is Electronic Numerical Integrator And puter). It was announced in the United States on February 15, 1946.
The "Moore Group" responsible for the development task consisted of four scientists and engineers Eckert, Moakley, Goldstein, and Box. The chief engineer Eckert was only 24 years old at the time. ENIAC: 30.48 meters long, 1 meter wide, covering an area of ??170 square meters, with 30 operating stations, which is about the size of 10 ordinary rooms, weighs 30 tons, consumes 150 kilowatts of electricity, and costs US$480,000.
It uses 18,000 electron tubes, 70,000 resistors, 10,000 capacitors, 1,500 relays, more than 6,000 switches, and performs 5,000 additions or 400 multiplications per second, which is 1,000 times that of a relay computer and manual calculation. 200,000 times. The idea of ??developing an electronic computer arose during the Second World War.
At that time, fierce fighting was going on, and the weapons and equipment of various countries were far behind what they are now. The main strategic weapons were aircraft and artillery. There were no "Scud" missiles, "Patriot" anti-aircraft missiles, or "Patriot" anti-aircraft missiles. Tomahawk" cruise missile, so it is very necessary and urgent to develop new cannons and missiles. To this end, the U.S. Army Ordnance Department established the "Ballistic Research Laboratory" in Aberdeen, Maryland.
The U.S. military requires the laboratory to provide 6 firepower tables to the Army Artillery Force every day for technical evaluation of missile development. Don't underestimate these 6 fire tables, they require an astonishing amount of work! In fact, each firepower table needs to calculate hundreds of ballistics, and do you know what the mathematical model of each ballistic is? A very complex set of nonlinear equations.
There is no way to find exact solutions to these equations, so numerical methods can only be used to calculate them approximately. But even using numerical methods to approximate the solution is not an easy task! According to the calculation tools at the time, even if the laboratory hired more than 200 calculators to work overtime, it would take more than two months to calculate a firepower table.
In the war era when "time is victory", how could such a slow speed be achieved? I'm afraid that even before advanced weapons are developed, defeat is already certain. In order to change this unfavorable situation, John Mauchly, who was then working at the Mauch School of Electrical Engineering at the University of Pennsylvania, proposed the initial idea of ??trial-producing the first electronic computer in 1942 - "the use of high-speed electron tube computing devices." It was hoped that electronic tubes would be used instead of relays to increase the computational speed of the machine.
When the U.S. military learned of this idea, it immediately allocated funds to support it and established a research team headed by Moshili and Eckert to start research and development work with a budget of US$150,000. This was a huge sum of money at the time. If it weren't for the war, who would be willing to spend such a huge amount of money! Although war is all evil, it does not occasionally promote the development of science and technology.
What made the development work very lucky was that the mathematician von Neumann (v.n weumann, a Hungarian-American) who was a consultant to the Institute of Ballistics and was participating in the development of the first atomic bomb in the United States With a large number of computational problems encountered during the development of the atomic bomb, he joined the development team in the middle of the development process. He made important contributions to the solution of many key problems of computers, thereby ensuring the smooth advent of computers.
Although ENIAC is huge in size, consumes an astonishing amount of power, and operates at a speed of only a few thousand operations (the fastest supercomputers today can do trillions of operations per second!), it is much faster than the computing devices that existed at the time. It is 1000 times faster, and it also has the function of automatically performing arithmetic operations, logical operations and storing data according to pre-programmed programs. ENIAC announced the beginning of a new era.
Since then, the door to scientific computing has also been opened. Of course people will not be satisfied with this! Since the advent of the first computer, more and more high-performance computers have been developed.
Computers have developed from the first generation to the fourth generation, and are currently developing towards the fifth and sixth generation intelligent computers. Like the original ENIAC, many high-performance computers are always serving the development of sophisticated and conventional weapons, especially nuclear weapons.
Like all tools invented by mankind, computers were born out of practical needs. Since the 18th century, the level of science and technology has made great progress.
The logic circuit knowledge and vacuum tube technology necessary to manufacture electronic computers had appeared and been perfected in the late 19th and early 20th centuries. Therefore, it can be said that the basic scientific knowledge for building computers is complete.
But why did the world's first electronic computer have to wait until the mid-1940s to come out? The main issues here are whether the actual needs are urgent and whether funds are in place. The practical need is of course always there, and who wouldn't want to own a state-of-the-art computing tool? But demand alone doesn’t determine everything.
The development of a new tool always requires a large upfront investment (when developing ENIAC, the initial investment was US$150,000, but the final total investment was as high as US$480,000, which was a huge investment in the 1940s. A huge amount of money!). There are always a few people who are brave enough to spend money on a tool that has not yet been invented.
In the end, it was the war that made the birth of the computer a reality. In fact, among various social needs, the needs during war are always the most urgent, because they are a matter of life and death.
The *** and the military are always generous and apply the latest scientific and technological achievements to the development of strategic and conventional weapons to ensure that they are in a leading position in the military. It was during the smoke of World War II that electronic computers began to be developed.
As mentioned earlier, in order to provide accurate and timely ballistic firepower tables for U.S. ordnance tests, a high-speed calculation tool was urgently needed. Therefore, with the strong support of the US military, the world's first electronic computer ENIAC began to be developed in 1943.
Participating in the development work is a development team headed by Mosely and Eckert of the Moore School of Electrical Engineering at the University of Pennsylvania. In the middle of development, the famous mathematician von Neumann joined the ranks.
After more than two years, ENIAC was successfully developed. In the spring of 1945, ENIAC's first trial operation was successful.
On February 10, 1946, the U.S. Army Ordnance Department and Moore College of the University of Pennsylvania jointly announced the birth of ENIAC to the world, which opened the prelude to the development and application of electronic computers. Now people.
3. Knowledge of each key on the calculator
The meanings of each key on the calculator are as follows: 1. Power on/all clear key (ON/AC): Press Pressing this key means powering on, or clearing the values ??in all registers.
2. Clear key (C): During digital input, pressing this key for the first time will clear all values ??except the memory content. 3. Clear input key (CE): Pressing this key during digital input will clear the value in the input register and display "0".
4. Square root √: Displays the square root of an input positive number. 5. M+: Put the currently displayed value in the memory; interrupt digital input.
6. M-: Subtract the current display value from the memory content; interrupt digital input. 7. MRC: Pressing this key for the first time will recall the memory contents, and pressing it for the second time will clear the memory contents.
8. MR: Recall memory content. 9. MC: Clear memory contents.
10. GT: Press the GT key to transfer the contents of the GT storage register to the display register; press the AC or C key to eliminate the GT display mark. 11. MU (Mark-up and Mark-down key): Press this key to complete the calculation of interest rates and tax rates.
12. MRC: The first press of this key will recall the memory contents, and the second press of this key will clear the memory contents.
4. How to use general calculators
Original publisher: Computer black screen 007
How to use calculators. Calculator tips. Common calculators such as I believe everyone can use some common functions of Deli calculator and Chenguang calculator. They often use them for addition, subtraction, multiplication and division to quickly calculate results. Some small function keys can get twice the result with half the effort, and many people may have never used these functions. I found some information on Shijiazhuang Office Supplies Wholesale Network, and based on my actual experience, I sorted out the functions and usage of those function keys. For a moment. M+: Put the currently displayed value in the memory, which is the calculation result plus the stored number. (If there is no "M" mark on the screen, that is, there is no data in the memory, the displayed value will be stored directly in the memory). M-: Subtract the current display value from the memory content. It is the calculation result and subtracts the current result from the stored number. If there is no number in the memory, press M- to store the negative display number. MS: Store the displayed content into the memory, and the original data in the memory will be washed away. MR: Pressing this key will call the memory content, which means reading the value in the memory to the screen and participating in the calculation as the current value. MC: Clear the memory content when pressed (the "M" mark on the screen is cleared). MRC: The first press of this key will recall the memory contents, and the second press will clear the memory contents. GT:GT=GrandTotal means the sum of the total, that is, all the numbers obtained after pressing the equal sign are accumulated and added and then transferred to the GT storage register. Press GT to display the accumulated number, press it again to clear it. MU (Mark-up and Mark-down key): Press this key to complete the calculation of interest rates and tax rates, see Example 3 for details; CE: Clear input key, pressing this key during digital input will clear the value in the input register and display "0 ", can be re-entered; AC: clears all data results and operators. ON/C: Power on/all clear key. Press this key to power on or clear the values ??in all registers. Usage examples: Example 1. Press 32*21 first, and the number is 672. Then press
5. Mathematical allusions, graphics, interesting calculations, small knowledge learned knowledge and extracurricular knowledge for grades 1 to 5
◆The story of pi 1. Zu Chongzhi, seven bits, the world First, it has been maintained for a thousand years; "The accuracy of the pi calculated by a country in history can be used as a measure of the country's mathematical development level at that time." 2.1427, *** mathematician Al Qasi, 16th; In 1596, the Dutch mathematician Rudolf ranked 35th; in 1990, the number of computers reached 480 million; on December 6, 2002, the University of Tokyo ranked 1,241.1 billion.
◆"0" There is no 0 in Roman numerals; in the fifth century, "0" was introduced to Rome from the East. At that time, the Pope was very conservative and believed that Roman numerals could be used to record any number and it was sufficient, so he banned it. With "0", a Roman scholar's manual introduced some uses of 0 and 0. After the Pope discovered it, he tortured it. ◆Measure the circumference of the world with "rules" and "rectitudes" In a stone chamber statue in an ancient building in Jiaxiang County, Shandong Province, there are two images of our ancient ancestors in ancient deifications, one is Fuxi and the other is Nuwa.
The object in Fuxi's hand is a ruler, which is similar to a compass; the object in Nuwa's hand is called a moment, which is in the shape of a right-angled ruler. The Drawer Principle in Ancient China In ancient Chinese literature, there are many examples of successful application of the Drawer Principle to analyze problems.
For example, in "Liangxi Manzhi" written by Fei Gun in the Song Dynasty, the drawer principle was used to refute the fallacy of superstitious activities such as "fortune telling". Fei Gong pointed out: The year, month, day and hour of a person's birth (horoscopes) are used as the basis for fortune telling, and the "horoscopes" are used as "drawers". There are only 12*360*60=259200 different drawers.
Taking the people of the world as "objects", there must be tens of thousands of people entering the same drawer, so the conclusion is that there are many people born at the same time. But since the "eight characters" are the same, "why are there any differences between the rich and the poor?" Qian Daxin's "Collected Works of Qian Yan Tang", Ruan Kuisheng's "The Guest Talk after Tea", and Chen Qiyuan's "Notes of Yongxianzhai" are all in the Qing Dynasty. Similar text.
However, it is regrettable that although Chinese scholars have long used the drawer principle to analyze specific problems, no general text about the drawer principle has been found in ancient documents. Abstracting it into a universal principle, this principle had to be named after the Western scholar Dirichlet hundreds of years later.
Application of the Drawer Principle In 1947, Hungarian mathematicians introduced this principle into the mathematics competition for middle school students. There was a question in the Hungarian National Mathematics Competition that year: "Prove that among any six people, you can definitely find three people who know each other. Or three people who don’t know each other.”
This question may seem bizarre at first glance. But if you understand the drawer principle, it is very simple to prove this problem.
We use A, B, C, D, E, F to represent six people. Find one of them at random, such as A, and put the other five people into "Knowing A" and "Don't know A" "Go into the two "drawers". According to the drawer principle, there are at least three people in one drawer. Let's assume that there are three people in the drawer of "Meet A", they are B, C, and D.
If B, C, and D do not know each other, then we have found three people who do not know each other; if two of B, C, and D know each other, for example, B and C knows each other, then A, B, and C are three people who know each other. In either case, the conclusion of this question is valid.
Due to the novel form of this test question and the clever solution, it soon spread widely around the world, making many people aware of this principle. In fact, the drawer principle is not only useful in mathematics, but also plays a role in real life, such as admissions, employment arrangements, resource allocation, professional title evaluation, etc. It is not difficult to see the role of the drawer principle.
Rabbits in the same cage Have you ever heard of the "chicken and rabbit in the same cage" problem before? This question is one of the famous interesting questions in ancient my country. About 1,500 years ago, this interesting question was recorded in "Sun Zi Suan Jing".
The book narrates this: "Today there are chickens and rabbits in the same cage. There are thirty-five heads on top and ninety-four legs on the bottom. How many are the chickens and rabbits? The meaning of these four sentences is: There are several chickens and rabbits in the same cage. Counting from the top, there are 35 heads; counting from the bottom, there are 94 legs. How many chickens and rabbits are there in the cage? Do you want to know? How does Sun Zi Suan Jing answer this question? The solution is as follows: If half of the legs of each chicken and each rabbit are cut off, each chicken will become a "one-horned chicken" and each rabbit will become a "one-horned chicken". It becomes a "two-legged rabbit"
In this way, (1) the total number of chicken and rabbit feet changes from 94 to 47; (2) if there is a rabbit in the cage, then The total number of legs is 1 more than the total number of heads. Therefore, the difference between the total number of legs, 47, and the total number of heads, 35, is the number of rabbits, that is, 47-35=12 (rabbits). Obviously, the number of chickens is 35-12=23. This idea is novel and unique, and its "foot-cutting method" has also amazed mathematicians at home and abroad.
This way of thinking. It is called the reduction method. When solving a problem, the reduction method does not directly analyze the problem, but deforms and transforms the conditions or problems in the problem until it is finally classified into a solved problem. .
Puchoko was a famous mathematician in the former Soviet Union and wrote the book "Primary School Mathematics Teaching Methods" in 1951.
This book contains the following. Interesting question. The store sold 1,026 meters of cloth in three days.
The number sold on the second day was twice that of the first day; the number sold on the third day was 3. Times. How many meters of cloth were sold in each of the three days? This question can be thought of as: The number of meters of cloth sold on the first day can be drawn as the following line graph: The first day is 1 share; the second day is 2 times the first day; the third day is 3 times the second day, that is, 2*3 times the first day, a comprehensive formula can be used to calculate the first day sales. The number of meters of cloth: 1026÷(l+2+6)=1026÷9=114 (meters) and 114*2=228 (meters) 228*3=684 (meters) So the cloth sold in the three days are: 114 meters, 228 meters, 684 meters.
Please answer this question. Four people donated money for disaster relief.
B’s donation is twice that of A’s. 3 times, Ding donated 4 times. They donated 132 yuan.
How much did each of the four people donate? There was a general named Han Xin in Guigu. For the first time, he only asked his subordinates to report the number by pressing 1~3, 1~5, 1~7, and then report the remainder of each team's count, and he would know how many people were there.
< p> His ingenious algorithm is called Guigu calculation, also called partition calculation, or Han Xin's strategy, and foreigners also call it it.