In a subtraction formula, the sum of the subtracted number, the subtracted number and the difference is 388. The subtracted number is 16 larger than the difference

In a subtraction formula, the sum of the subtracted number, the subtracted number and the difference is 388. The subtracted number is 16 larger than the difference

Subtracted: 388 / 2 = 194
Poor: 194-16 = 178
Subtraction: 198-178 = 16

In a subtraction formula, the sum of the subtracted, the subtracted and the difference is 388. If the subtraction is 16 larger than the difference, what is the subtraction?

Because
Subtracted = difference + subtracted
therefore
What is the sum of difference and subtraction
388÷2＝194
What is the subtraction
（194＋16）÷2＝105

In a subtraction formula, the sum of the subtracted, the subtracted and the difference is 388?

Let the minus be X
Formula: x + (x-16) + X + (x-16) = 388
4X=420
X=105
A: the minus is 105

In the quadrilateral ABCD, angle B = angle d = 90?: four points of ABCD are on the same circle
Note: angles B and D are diagonal

Connect AC, take the midpoint o of AC, connect OB and OD
Because angle B = 90 degrees, O is the midpoint of AC
So ob = OA = OC
Similarly, OD = OA = OC
So OA = ob = OC = OD
So a, B, C and D are on the circle with o as the center and OA as the radius
So a, B, C, D are on the same circle

Who invented abacus?

In the 15th century, Xu Yue invented the abacus
Chinese
In the last years of the Eastern Han Dynasty, Xu Yue recorded in the book of numerology, when his teacher Liu Hong visited the hermit Mr. Tianmu, Mr. Tianmu explained 14 kinds of calculation methods, one of which was abacus, and the calculation tool used was very close to the modern abacus. Each abacus had five movable beads, one of which was equivalent to five, and the other four were regarded as one
At the end of the Eastern Han Dynasty, Mr. Tianmu
Xu Yue of Han Dynasty
Abacus is a computing tool that everyone is familiar with. Who was the inventor of abacus? What's the exact year of its invention? We first saw the word "abacus" from Xu Yue's book "a legacy of numerology" in the Eastern Han Dynasty. However, the annotation says that it can only do addition and subtraction. Today, this is at most a rudiment of abacus, Abacus was invented in the song and Yuan Dynasties. Zhizhisuao Tongzong (1592), written by Cheng Dawei in the Ming Dynasty, was the most widely spread and influential work on abacus at that time. People have looked up a large number of historical documents. From the song and Yuan Dynasties to the era of Cheng Dawei (1553-1606), they can't find the name of the inventor of abacus, The same is true of the above-mentioned calculation and research, which shows that the feudal rulers did not pay enough attention to scientific and technological inventions. On the other hand, it also shows that their invention was a gradual process, which was gradually improved and perfected. It is hard to say who contributed to it. Abacus is derived from the advancement of calculation. Due to the development of society, the demand for speed and accuracy of calculation is higher and higher, For example, the formula of 14 + 7 is "seven divided by three into one", similarly, the formula of 14-7 is "seven retreated, one returned to three", and so on. All addition, subtraction, multiplication and division have a set of formulas. In fact, before the advent of abacus, except for individual division formulas, Almost all the abacus formulas have been completed. After the emergence of the formulas, the speed of calculation has increased. If you continue to manipulate the abacus for calculation, you will not be able to follow your heart. Due to the limitations of the objective environment, many business people who do calculation outdoors are especially prone to confuse the abacus and make mistakes, It was in this case that craftsmen, calculators and businessmen of that time worked together to develop a clever abacus. The similarities between abacus and arithmetic chips are obvious. In arithmetic chips, one upper chip should be five, and one lower chip should be one; in Pearl abacus, one upper pearl should be five, There is an agreement in the calculation called "five not single", which means that 5 can not be expressed by one single chip. This is the reason why there are five beads in the abacus. Experts in the history of mathematics can also find the basis for the calculation of two beads in the abacus, Abacus is one of the important scientific achievements in ancient China. It has the advantages of simple structure, simple operation and convenient carrying, so it has been widely used for a long time. Up to now, abacus is still a compulsory course for primary school students in our country. Although all kinds of electronic computers and electronic calculators have been quite popular in the market, when adding and subtracting method is used, abacus is still a compulsory course for primary school students, Their computing speed still can't catch up with the abacus in the hands of skilled abacus operators. After abacus became popular in China, it spread to Korea, Japan, Southeast Asia and Arabia, making an important contribution to the world civilization. China is the hometown of abacus. Today, when computers are widely used, the ancient abacus has not been abandoned, On the contrary, because of its flexibility and accuracy, it is in the ascendant in many countries. Therefore, people often compare the invention of abacus with the four great inventions of ancient China, and think that abacus is also a great contribution of the Chinese nation to mankind. However, when did China begin to have abacus? Since the Qing Dynasty, many mathematicians have studied this problem, Japanese scholars have also devoted a lot of energy to this issue. Due to the lack of sufficient evidence, the origin of abacus is still controversial. To sum up, there are three main theories. One is the Eastern Han Dynasty and the southern and Northern Dynasties advocated by Mei Qizhao, a mathematician in the Qing Dynasty. The basis is that Xu Yue, a mathematician in the Eastern Han Dynasty, wrote a book "the legacy of numerology", in which 14 algorithms are described, Later, Zhen Luan, a mathematician of the Northern Zhou Dynasty, annotated this passage, saying: "the rigidity is divided into three parts, the upper and lower two parts to stop the Pearl, and the middle one part to calculate the position. Each of them has five pearls. The upper and lower four pearls are different in color. The upper and lower four pearls are five, and the lower four pearls are one, These words are considered to be the earliest records of abacus. However, some scholars believe that the abacus described in this book is at best a counting tool or a simple calculation board that can only be used for addition and subtraction, Second, Qian Da Ting, a scholar in the Qing Dynasty, advocated that abacus appeared in the middle of the Yuan Dynasty and was widely used in the late Yuan Dynasty and early Ming Dynasty. Jingzhu, the 29th volume of Tao Zongyi's Nan Cun Tuo Geng Lu in the Yuan Dynasty, quoted the proverb at that time to describe the servants, saying: "when the vassal maidservant first came, he would challenge the abacus bead, but his words would not move automatically; a little longer, he said abacus bead, and his words would move; after a long time, he said Buddha's top bead, In the late Song Dynasty and the early Yuan Dynasty, Liu Yin wrote a five character quatrain with the title of abacus: "don't do Weng Shang dance, stop the cake song, As for the Ming Dynasty, in the Lu Ban Mu Jing compiled in the Yongle period, there were specifications and sizes of abacus, as well as works on abacus usage, such as Xu Xinlu's suanzhou algorithm and Cheng Dawei's Zhizhi Suan FA Tongzong. Therefore, there is no doubt that abacus was widely used in the Ming Dynasty, The third theory that abacus originated in the Tang Dynasty and was popular in the Song Dynasty is based on the following: first, in the famous painting "Qingming Shanghe Tu" of the Song Dynasty, there is a medicine shop with an abacus on the front counter. After the abacus experts of China and Japan photographed and enlarged the picture, they confirmed that the object in the painting is a serial abacus similar to the modern abacus, In 1921, a wooden abacus bead was excavated in Julu County, Hebei Province. It has been submerged for 800 years, but it is still drum shaped with holes in the middle, which is no different from modern abacus beads. Third, Liu Yin was born in the late Song Dynasty and the early Yuan Dynasty. His abacus poem is not so much a description of things in the Yuan Dynasty as a reflection of things in the Song Dynasty, According to Tao Zongyi's "Sanzhu Xiyu", there is a saying about abacus beads in the proverbs of the Yuan Dynasty, which also reflects that "the method prevailed in the Song Dynasty" (the article "algorithmic Tongzong" in the synopsis of Sikuquanshu). Fourth, there is a nine file map of abacus in the elementary school textbook "xinbian xiangsiyan" in the early Yuan Dynasty, In addition, the abacus in the Song Dynasty was more mature in shape, without the clumsiness or coarseness of new things. Therefore, many mathematicians believe that the birth of abacus can be extended to the Tang Dynasty, Abacus is less likely to be born at this time. However, the Tang Dynasty is a prosperous age in Chinese history, and its economy and culture are more developed. New computing tools are needed. The two thousand year old abacus evolved into abacus at this time, and it is very likely that abacus was invented at this time. Abacus is a valuable cultural heritage of the Chinese people, but its origin has been debated for hundreds of years, I hope more and more people will devote themselves to further exploration and research, and draw scientific conclusions as soon as possible, so as to comfort the ancients and be worthy of the future generations. The abacus, which symbolizes "multiplication and division without loss, is often used to symbolize careful calculation, without error. In the express News Department of Dongyue Temple in Beijing, there are two big abacuses, 6 feet long and 2 feet high, There are 29 squares and 203 abacus beads in total. This abacus shows that the gods calculate the merits and demerits of the next generation
Abacus is a method of numerical calculation using abacus as a tool. The word "abacus" first appeared in the book of numerology written by Xu Yue in Han Dynasty, which said: "abacus controls four seasons and three talents of longitude and latitude." Zhen Luan of Northern Zhou Dynasty made a note to this effect. The main idea is to carve the wooden board into three parts, the upper and lower parts are used for stopping and swimming beads, and the middle part is used for positioning, The color of the upper bead is different from that of the lower four beads. The upper bead should be five, and the lower four beads should be one

What is the evolution of abacus?

It should be evolved from "planning". Planning is to use a bamboo stick as a chip to calculate
ps：
I am also in Baidu Encyclopedia to find you to see Baidu information

Who knows the formula of mental arithmetic?

Abacus formula table so-called abacus, that is, abacus formula. Abacus, abacus is used as a tool to calculate the number of multiple add, subtract, multiply, divide, four calculation, square and other types of questions

How to teach children to add and subtract finger speed algorithm within ten

How to teach finger speed algorithm one, examples should be close to life, to choose children's most familiar. Things in life are children's most familiar. Therefore, the teacher may choose some children's more familiar examples when giving examples. For example, when learning carry law two (thumb from extension to flexion into one), children should carry and when to enter

Magic formula! Letters! After the cross!

The corner block turns clockwise and the fish head is placed at the bottom right R 'U2 r u r' u r
The corner block is turned anticlockwise and the fish head is placed on the top right r u '2 R' U 'r u' R '. If you don't like to remember this, you can use it clockwise twice
Depending on the above formula can complete the top multicolor
L f 'L B & # - 178; l F L B & # - 178; L & # - 178; this is to restore the corner. Remember that two corners of the same color should be facing away from you
(r u 'R) U (r u r u') (R 'U' R2) this is a block that rotates clockwise. You can do everything with these formulas
.(R2' U)(R U R' U')(R' U