注目の話題
付き合った彼氏実は結婚していた
嫁がいるのに恋してしまいました
車中泊で職質されますか?

Science,English,and math 4th

レス500 HIT数 30075 あ+ あ-

匿名さん
21/05/07 20:00(更新日時)

I will start from now on

(兄の英語スレをよろしく‼)


No.3244915 21/02/28 23:15(スレ作成日時)

新しいレスの受付は終了しました

投稿制限
ハンドル名必須
投稿順
新着順
主のみ
付箋

No.351 21/04/18 18:39
燻し銀三 ( 60代 ♂ IJ7P0b )

【An imaginary number and quantum computer】

But even if the imaginary number on the plane of coordinates becomes visible for us, as the number doesn’t exist actually, what is the use of inventing the number and discussing about it? Lots of people may have thought like that, and I myself think so as well.

Quantum mechanics 量子力学 deals with a microscopic world, and a thing of which we can’t think from our common knowledge takes place there.

The material has both nature of a particle and a wave at the same time, a single material exists in other places at the same time. The material is...

No.352 21/04/20 18:52
燻し銀三 ( 60代 ♂ IJ7P0b )

【The imaginary number and quantum computer】

The material is born from a vacuum where there is nothing, or vanished there. It sometimes passes through a wall, so the complex number is indispensable so as to describe physics in the world of the quantum physics.

As you know I have none of knowledge on the quantum physics, so I’ve expressed the mysterious things, but it’s just that I did as the book showed. I want to express it why, but to my sorrow I can’t do at present.

The quantum physics is the base on modern scientific techniques. It is no exaggeration that without the quantum physics...

No.353 21/04/20 19:09
燻し銀三 ( 60代 ♂ IJ7P0b )

【The imaginary number and quantum computer】

It is no exaggeration that without the quantum physics neither smartphone nor personal computer were never born.

For example, a quantum computer about which we are much talked is put the theory on quantum physics to practical use and is made.

While the computer proceeded a calculation with 1 or 0 in the past, the quantum computer makes use of a situation that the number is 1 and 0, its speed on calculation becomes high speed.

Without the quantum physics, in other words, without the complex number, we the humankind couldn’t have established...

No.354 21/04/20 19:24
燻し銀三 ( 60代 ♂ IJ7P0b )

【The imaginary number and quantum computer】

Without the quantum physics, it means without the complex number, we the humankind couldn’t have established the modern civilization.

Not only we can describe the microscopic world with the complex number but without ending in failure the relative theory by Einstein we’ve succeeded in expressing the beginning on the universe by using the time of complex number, Dr. Hawking said like that.

To my sorrow, I can’t understand it in the least.

《Keen insight on Leibniz》

The author said that the complex number is indispensable in modern physics, but...

No.355 21/04/20 19:45
燻し銀三 ( 60代 ♂ IJ7P0b )

【Imaginary number and quantum computer】

《Keen insight on Leibniz》

I’m afraid I’ve confused the complex number and imaginary number. I’m sorry for it.

We need some numbers which don’t exist actually so as to express our real world, but there seem to be some people who think it doesn’t make sense to them.

Kronecker who is a mathematician said like the next.

While the God has created natural number like 1,2,3..., except for them, we the humankind has introduced new concepts and contrived all the other numbers like 0, minus numbers, a decimal, a fraction, or irrational numbers and we’ve ...

No.356 21/04/20 20:03
燻し銀三 ( 60代 ♂ IJ7P0b )

【Imaginary number and quantum computer】

《Keen insight on Leibniz》

...and we’ve expressed unknown world until now.

As we need a new kind of number of irrational number so as to express the length on the oblique side 斜辺 of a right angle isosceles triangle, in the same way, the complex number is indispensable and useful when trying to express the microscopic world in a compact way clearly.

It is said Leibniz said on the imaginary number like the next.

The God appears its figure in sublime way as miraculous product which drifts existence and non existence.

Leibniz was sixty years older...

No.357 21/04/20 20:25
燻し銀三 ( 60代 ♂ IJ7P0b )

【Imaginary number and quantum computer】

《Keen insight on Leibniz》

Leibniz is sixty years older than Euler, so he may have thought the significance on existence of the number which is squared is minus by far more earlier than Euler, before Euler studied on imaginary number in earnest and announced its income. If so he is awesome genius.

【A magic square is a good exercise for the brain】

《Simple and profound mathematical puzzle》

Pythagoras in the Ancient Greece said everything is number, Galileo said the universe is written by a language of math. It is certain that strictness and ...

No.358 21/04/20 21:44
燻し銀三 ( 60代 ♂ IJ7P0b )

【A magic square is a good exercise for the brain】

《A simple and profound mathematical puzzle》

It is certain that strictness and rationality in math is suitable to solve the truth on the universe.

Even if not being a scientist, if wanting to get to its own conclusion among various senses of values everyday life, mathematical ability of thinking way is necessary. Development on IT where technical skill on information has been made full use of and and the rise of artificial intelligence makes us feel something significant on math day by day.

If we’re the one who has lived in the modern era...

No.359 21/04/20 22:02
燻し銀三 ( 60代 ♂ IJ7P0b )

【A magical square is a good exercise for the brain】

《A simple and profound mathematical puzzle》

...we have to master the statistical literacy, but we’re sick and tired of hearing that, but it doesn’t always that math exists for the refined target alone, for math frequently appears in a thing like a game.

When gambling, if having some knowledge on probability, it is profitable for us. Besides when creating lots of puzzles, math has been taken advantage of then, especially a magical square is famous among the mathematical puzzle and has had a long history. What is the magical square?

No.360 21/04/20 22:20
燻し銀三 ( 60代 ♂ IJ7P0b )

【A magical square is a good exercise for the brain】

《A simple and profound mathematical puzzle》

There is a square, and there are some other small squares in the square, each of small square has each number which is different between each other. Even if adding up each of number of vertical, horizontal or diagonal line, its total number is the same, but we can’t use the same number twice.

There is an illustration on the magical square which is 3×3 in the book. When adding the number in every vertical line, in every horizontal line and in diagonal line,..

No.361 21/04/20 22:41
燻し銀三 ( 60代 ♂ IJ7P0b )

【A magical square is a good exercise for the brain】

《A simple and profound mathematical puzzle》

...it’s 15 in total. In general, the magical square on 3×3 is the magical square on the third order. The square is made up with other small nine squares, three lines each of vertical and horizontal.

If the magical square is made up with n×n, we call it nth order.

《A pattern on the shell of a holy tortoise》

How is the number of 15 kinds of number lined in the magical square? When turning it over or rotating, if regarding them as the same one, the magical square in which the number from 1 to 9...

No.362 21/04/20 23:01
燻し銀三 ( 60代 ♂ IJ7P0b )

【A magical square is a good exercise for the brain】

《A pattern on the shell of a holy tortoise》

...the magical square on which each number from 1 to 9 is used in the third order is one kind alone. The number of line from upper right,294753618. There is a comical variations of idioms 語呂合わせ on the numbers. 憎し 294 七五三、六一坊主に蜂が刺す.

As to other magical square on the fourth order 4×4 in which each number from 1 to 16 is used turned out to be 880 kinds.

Another one on the fifth order 5×5in which each number from 1 to 25 is proved to be about two hundred million seven thousand kind.

One more on ...

No.363 21/04/21 06:22
燻し銀三 ( 60代 ♂ IJ7P0b )

【A magical square is a good exercise for the brain】

《A pattern on the shell of a holy tortoise》

It turned out that the magical square on the sixth order of 6×6 is more than seventeen quintillion 1700 京 in which the number from 1 to 36 is used.

The bigger the ordinal number is, the more its kind increases by leaps and bounds.

The magical square is originated in China. A tortoise was picked up by a Chinese Emperor in the Yellow River, and it is said that there was the magical square of third order with the same number of points from 1 to 9 is described on the shell.

The Chinese Emperor ...

No.364 21/04/21 06:33
燻し銀三 ( 60代 ♂ IJ7P0b )

【A magical square is a good exercise for the brain】

《A pattern on the shell of a holy tortoise?》

The Chinese Emperor got together principles on politics and economy and divided it into nine, for it is said the pattern on the shell of a holy tortoise was divided into nine, and a fortune-telling of 九星術 was born from the pattern of the shell.

We’ve enjoy ourselves on the magical square as a mathematical puzzle at present, but it used to be thought to be something mysterious in the past.

The magical square was born and was spread over the Western area, but it was unclear how it was done then.

No.365 21/04/21 06:49
燻し銀三 ( 60代 ♂ IJ7P0b )

【A magical square is a good exercise for the brain】

《A pattern on the shell from a holy tortoise》

There are some variations on the magical squares like the one which is made up with square measures 平方積, and the other with prime numbers 素数 alone.

《A written challenge to readers on the magical square》

The author said he wanted us all of the readers to complete the magical square on the book, and he said he would be happy if we tackle it as a good exercise for the brain.

But even if trying to put each number in the magical square at random, we can’t complete it easily, so the author...

No.366 21/04/21 07:03
燻し銀三 ( 60代 ♂ IJ7P0b )

【The magical square is a good exercise for the brain】

《A written challenge to readers on the magical square》

...the author showed us some bases when tackling the magical square.

When creating the magical square of 4×4, each of the total number on the vertical, horizontal and diagonal line is always 34, and the author said he was going to say its reason later.

He has already put some of numbers in the magical square beforehand, and we have to be careful of numbers which we can use. It’s from 1 to 16, and we need to look for a line of which number is either extremely large or small...

No.367 21/04/21 07:18
燻し銀三 ( 60代 ♂ IJ7P0b )

【The magical square is a good exercise for the brain】

《A written challenge to readers on the magical square》

...and we need to look for a line of which number is either extremely large or extremely small., and to limit the candidacy for the number from there.

Why is the total number on the magical square of each vertical, horizontal, and diagonal line 34?

As to the fourth order of magical square, each number from 1 to 16 is used in the squares of 4×4, and if adding all the numbers, it’s 136. It means that the total number on the four lines are 136, so the total number on the single line...

No.368 21/04/21 08:05
燻し銀三 ( 60代 ♂ IJ7P0b )

【A magical square is a good exercise for the brain】

《A written challenge to readers on the magical square》

...so the total number on the single line is found dividing 136 by four, and it’s 34.

Some numbers which were lined on the magical square of 4×4 is like the next.

I recommend you describe the number actually, for it’s easy to understand.

The top on the horizontal line, there is 4 on the left corner and next to the 4 is vacant. There is no number there. The next place to the vacant is 15, and the right corner is also vacant.

The second line from the top. There is 8 in the left end...

No.369 21/04/21 08:24
燻し銀三 ( 60代 ♂ IJ7P0b )

【A magical square is a good exercise for the brain】

《A written challenge to readers on the magical square》

...and there are blank on other three small squares. There is 8 alone at the right end of the second line from the top.

The third line from the top. Its left side is blank and its next is 7, and other two are blank as well.

The bottom line. Its left corner is blank and its next is 2 and next to 2 is 3. The right corner is blank.

An example on a way of thinking.

There are some numbers which weren’t put in the magical square yet like 1, 5, 6, 9, 10, 11, 12, 13, 14, and 16.

We name...

No.370 21/04/21 14:14
燻し銀三 ( 60代 ♂ IJ7P0b )

【A magical square is a good exercise for the brain】

《A written challenge to readers on the magical square》

We need to name each of the blank square one by one. At the top from the left, between 4 and 15, we call it A, and the right corner at the top, it’s B.

At the second line from the top, there are three blank squares. We call C, D, and E from the left.

At the third line from the top, there are also three blank squares. The left side next to 7, we call it F. Other two which are right to 7, they are G, and H, from the left.

At the bottom, the left corner is I and the right corner is J.

No.371 21/04/21 14:38
燻し銀三 ( 60代 ♂ IJ7P0b )

【A magical square is a good exercise for the brain】

《A written challenge to readers on the magical square》

Please write down actually what I’ve said until now.

At first we pay attention to the bottom. Its total number should be 34, and there are two kind of numbers there, 2 and 3, so it turned out that I+J=29.

When looking at the numbers which have never used in the magical square, I,J is (16,13)or(13,16), so at first we think of the case that I, J is 16, 13.

In the next, we think of the vertical line on the second from the left, and there is two kind of numbers there, 7 and 2, so the...

No.372 21/04/21 14:58
燻し銀三 ( 60代 ♂ IJ7P0b )

【A magical square is a good exercise for the brain】

《A written challenge to readers on the magical square》

...so the rest number in total, A+D=25, so A, D is 14,11 or 11, 14. If A,D is 11, 14, then B is 4, so it’s not appropriate, for 4 has already been used. Each of number is limited to use only once, so A,D is 14,11.

The rest of each number which has never been used is 1,5,6,9,10, and 12. If reaching until here, it’s easy, for each number in total on the rest line is 34, so we can fill the number in the magical square, so it’s completed.

【Do you know a pair of scales which is almighty?】

No.373 21/04/21 15:18
燻し銀三 ( 60代 ♂ IJ7P0b )

【Do you know a pair of scales which is almighty?】

《Look for a false coin!》

There is a question like the next. There are eight coins, and one of them is false, and the false one is a little heavier than the genuine ones.

A pair of scales has already been prepared for us so as to tell the coins between false and genuine.

Whichever we take any case, we want to distinguish the fake one from the genuine ones. How many times at least should we use the pair of scales to look for the fake one?

If you want to think it over slowly and carefully, I’m sorry for it, for the author said its answer...

No.374 21/04/21 15:34
燻し銀三 ( 60代 ♂ IJ7P0b )

【Do you know an almighty pair of scales ?】

《Look for a false coin!》

...the answer is twice. You may have thought, only twice? The author expressed its concrete way like the next.

The first time, we choose six coins at random and put them on the both of the scales by every three coins. If they are balanced, the fake is either of the rest two. If the scale is leaned on the one side, the fake one is among the three on the scale which was leaned.

The second time. When being balanced, we put the rest of the two coins on the scale one by one, and the one is leaned, so it’s the fake.

No.375 21/04/21 16:25
燻し銀三 ( 60代 ♂ IJ7P0b )

【Do you know an almighty pair of scales w】

《Look for a false coin!》

If leaning on the one side, taking the three coins form the leaning scale and put them on each of the scale again one by one. If being balanced, the rest one is the fake, and if being leaning on one side, the one on the leaning scale is the fake.

Then how about 20 coins? Even if the coin increases to 20, we can point out which coin is false as long as we used the pair of scales three times.

At the first time, we choose eighteen coins at random and put every nine coin on each of the scale. If being balanced, the rest...

No.376 21/04/21 19:38
燻し銀三 ( 60代 ♂ IJ7P0b )

【Do you know an almighty pair of balances?】

《Look for a false fake!》

If leaning on one side, the fake is among the nine coins on the leaning scale.

At the second time, if balancing at the first time, putting the rest of two coins one by one on the each scale, and the leaning one is the fake.

If leaning at the first time, taking nine coins from the leaning scale and put the coins three by three on each of the scale. If being balanced, the fake is among the rest of the three. If being leaning, the fake is among the three on the leaning scale.

At the third time, when being leaning at the...

No.377 21/04/21 19:50
燻し銀三 ( 60代 ♂ IJ7P0b )

【Do you know an almighty pair of balances?】

《Look for a fake coin!》

At the third time, if leaning in the first time, taking the three coins which turned out to be including the fake coin among them and put one by one on each of the scale. If being balanced, the rest one is the fake. If being leaned, the coin on the leaning scale is the fake.

To tell the truth, if thinking it with the same way, we can point out the fake coin until 27 coins as long as we can use the pair of scales. In addition, the number of the coin is 3 to nth power, it means that the number of coins is a multiple of 3...

No.378 21/04/21 20:04
燻し銀三 ( 60代 ♂ IJ7P0b )

【Do you know a almighty pair of scales?】

《Look for a fake coin!》

...it means that if the number of coins is a multiple of 3, we can point out the fake coin as long as we can use the pair of scales n times.

Except for the examples which were shown until now, the author recommended we try to count various number of coins, and think of the way of finding the fake coin. He said it will be a good exercise for the brain.

《A question in which a sense of mathematic is necessary for us》

The author said there is one more question and he said he wanted us to think it over. It’s in relation to the...

No.379 21/04/21 20:30
燻し銀三 ( 60代 ♂ IJ7P0b )

【Do you know an almighty pair of scales?】

《An question in which a sense of mathematics is necessary for us》

The question is relation to the pair of scales.

When using the pair of scales, and wanting to measure from 1 gram to 40 gram one by one gram, how many weight do we need at least? And how much is each of the weight?

If the one who is get used to it, it will answer we need six kinds of weight. 1 gram, 2 gram, 4 gram, 8 gram, and 16 gram.

If making use of the six kinds of weight, we can measure all the weight from 1 gram to 40 gram. All the weight is expressed with 2 to nth power.

No.380 21/04/21 21:56
燻し銀三 ( 60代 ♂ IJ7P0b )

【Do you know an almighty pair of scales?】

《A question in which a sense of mathematic is necessary for us》

1 is thought to be 2 to the 0th power in math. There is a list on the book, and what kind of weight like 1 gram, 2 gram, 4 gram, 8 gram, 16gram and 32 gram,is used for the weight is used is expressed on the list.

While the number which we usually use for every digit in the decimal system is from 0 to 9, the number which we usually used for the binary system is either 0 or 1 alone.

When 0 is adopted, it means that a thing isn’t adopted, and 1 is done, it means that something is used.

No.381 21/04/21 22:10
燻し銀三 ( 60代 ♂ IJ7P0b )

【Do you know an almighty pair of scales?】

《A question in which a sense of mathematics is necessary for us》

For example, when expressing 13 with the binary system, it's 1101, and it means that we measure something of which with each of single weight of 13 gram with a weight of 8 gram, 4 gram and 1 gram.

Though I can’t understand when 13 is expressed with the number of the binary system, 1101, why do we adopt those three kind of weigh? The total weight of the three kind is 13, I know why it is, but I’m not sure that the relation of the number which is expressed with the binary system and...

No.382 21/04/21 22:39
燻し銀三 ( 60代 ♂ IJ7P0b )

【Do you know an almighty pair of scales?】

《A question in which a sense of mathematic is necessary for us》

...but I’m not sure the relation between the number which is expressed with the binary system, 1101 and three kinds of weight, 1 gram, 4 gram and 8 gram.

The author continued, all the numbers in decimal system are expressed with those in the binary system, we have only to prepare for every weight of binary system one by one. It’s enough. Why?

To return to our main subject, I’ll start again.

But for example, how about in a case when we have to prepare for a weight of 4 to nth power?

No.383 21/04/25 08:19
燻し銀三 ( 60代 ♂ IJ7P0b )

【Do you know an almighty pair of scales?】

《A question in which a sense of mathematical is necessary for us》 

Then we think it of with quaternary in which number from 1 to 3 in every digit. When trying to express 13 with the quaternary, it’s 31. Why?

Its numerical equation is 3×4+1×0=13

When trying to express with English, 3 multiplied by four to the first power plus 1 multiplied by four to the 0th power, then three means three weight is used. Then 1 is 4 to the 0th power, it means a single weight is used. It’s 31, so 13 is equal to 31 when changing from the decimal system to quaternary.

No.384 21/04/25 08:46
燻し銀三 ( 60代 ♂ IJ7P0b )

【Do you know an almighty pair of scales?】

《A question in which a sense of mathematic is necessary for us》

In the same way when expressing 31 with the binary system, 8+4+1, it means that 1×2 to third power +1×2 to the second power+1×2 to 0th power. Three weight of 2 gram, two weight of the two grams, and a single weight of 1 gram is used. It’s 1101.

As to the binary system, if its digit is used, then putting 1, and if it’s not used, then putting 0.

The author continued his theory on the almighty pair of scales, but I don’t feel like expressing, for I find it boring. I’m sorry for it.

No.385 21/04/25 09:02
燻し銀三 ( 60代 ♂ IJ7P0b )

【A way of changing our both hands into an electronic calculator】

《There is few countries in which learning the multiplication table by heart》

We the Japanese learn the multiplication table in the second grade of elementary school. Learning the multiplication table may be the first deadlocked in arithmetic.

Everyone has memory of trying to learn it by heart with rhythmically, but a country where learning the multiplication table from 1 to 9 by force is few in the world.

For example, when learning it in the area of English speaking, a list of times table is used. The multiplication from...

No.386 21/04/25 09:19
燻し銀三 ( 60代 ♂ IJ7P0b )

【A way of changing both of our hand into an electric calculation】

《Few countries where leaning the multiplication tables by heart》

A list of multiplication table is used in the area of English spoken when learning the multiplication. There are multiplications to 12×12.

If going on using the list of the time table, they’ll learn it by heart automatically, and it’s all right, in America or Australia they’ve thought like that.

Why is it to 12×12?

1 feet is 12inch, and 1 dozen is 12, though it has been abolished, 1 shillings used to be 12pence in England, for the duodecimal system 12進法 is...

No.387 21/04/25 09:48
燻し銀三 ( 60代 ♂ IJ7P0b )

【A way of changing both of our hands into an electronic calculation】

《Few countries where learning the multiplication table by heart》

...for the duodecimal system is so frequently used in their everyday life that they have to adapt themselves to the duodecimal system.

《Japan where the electronic calculation has been forbidden》

Learning the multiplication table by heart has never been done by force in lots of foreign countries, for it may be related with the fact that they can use the electronic calculation at will in junior high school.

An questionnaire that whether or not they allow...

No.388 21/04/25 09:59
燻し銀三 ( 60代 ♂ IJ7P0b )

【A way of changing both of our hands into an electronic calculator】

《Few countries where learning the multiplication table by heart》

An questionnaire was done that whether they have allowed the students to use the electronic calculator in the class of math or arithmetic over some of foreign countries.

At the time of the fourth grade in elementary school, almost all of the countries, including Japan, have never allowed it, but the second grade in junior high school, the countries in which they allow to use the electronic calculation at will have increased so much.

After 10 years old...

No.389 21/04/25 10:17
燻し銀三 ( 60代 ♂ IJ7P0b )

【A way of changing both of our hands into an electronic calculator】

《Few countries where an electronic calculator has been prohibited》

After the age of 10 when cultivating an ability of logical thought, they want the children to spend on more time to think over something more logical rather than a simple work like the calculation.

On the contrary, teachers who allow the students to use the electronic calculator at will at the second grade in junior high school accounts for no more than 6% in Japan.

While the electronic calculator made in Japan has been used at school all over the world...

No.390 21/04/25 10:30
燻し銀三 ( 60代 ♂ IJ7P0b )

【A way of changing both of our hands into an electronic calculator】

《Japan where an electronic calculator has been prohibited》

...ironically the electronic calculation has hardly used in the class of Japan, but if the country where the electronic calculator is forbidden to use at will and learning the multiplication table by heart by force has higher mathematical ability, carrying out the education of Japanese style is significant, but unfortunately, there is none of the situation.

Hong Kong and Singapore where the electronic calculator has been used at will have higher mathematical ...

No.391 21/04/25 11:05
燻し銀三 ( 60代 ♂ IJ7P0b )

【A way of changing our both hands into an electronic calculator】

《Japan where the electronic calculation has been forbidden》

Hong Kong and Singapore where the electronic calculator has been used at will have higher mathematical ability in the questionnaire before. In addition there are lots of reports that if making the student use a tool for calculation like the electronic calculator or the list for multiplication table,it enhances their mathematical ability.

When trying to learn the multiplication table by heart, we Japan muttering rhythmically, but it seems to be strange for the....

No.392 21/04/25 11:22
燻し銀三 ( 60代 ♂ IJ7P0b )

【A way of changing both of our hands into an electronic calculator】

《Japan where the electronic calculator has been forbidden》

....but it seems to be odd for the Europeans and Americans who don’t have a habit of learning the multiplication table by heart. They thought we the Japanese looked as if we had muttered an incantation or something.

《Having a good command of the multiplication by counting on our fingers》

An expression on 九九 which is the multiplication table in Japan has been deep-rooted in Japanese life.

For example, 四六時中, 4×6=24, at the time of 24 hours a day, around the clock...

No.393 21/04/25 11:39
燻し銀三 ( 60代 ♂ IJ7P0b )

【A way of changing both of our hands into an electronic calculator】

《Having a good command of multiplication by counting on our fingers》

...18番 2×9=18, the one with expressed with the number of 2 and 9, it means that the one who we tend to hate, 29い奴, it has changed into an artistic skill on an actor who has popular among us.

28ソバ, 2×8=16, the price of a bowl of soba used to be 16文 in Japan in the past.

A culture of making the people learn the multiplication table by heart has existed in Japan, China, India, and other countries in Asia from long long ago, but except for the countries...

No.394 21/04/25 11:50
燻し銀三 ( 60代 ♂ IJ7P0b )

【A way of changing both of our hands into an electric calculation】

《Having a good command of multiplication by counting on our fingers》

...except for the countries how did they multiple, especially at the time when there was no electronic calculator, for they couldn’t carry the list of the multiplication table with them everywhere around the clock.

Without learning the multiplication table by heart, nor carrying the list of the multiplication table with them, a way of being able to do an easy multiplication was contrived around 15 century. It’s the multiplication by counting on fingers.

No.395 21/04/25 12:18
燻し銀三 ( 60代 ♂ IJ7P0b )

【A way of changing both of our hands into an electronic calculator】

《Having a good command of multiplication by counting numbers on fingers》

Without clenching our fist, opening our hands, bending from the thumb to the little finger one by one when calculating , and an order on 8×6 is shown in the book like the next.

1 Counting 8 on fingers in one hand and 6 is with other hand.

2Adding the number of bending fingers on both hands. 2+4=6

3Subtracting 6 from 10, and multiplying 10 by 4, 10−6=4, and 4×10=40

4 Multiplying each number of bending fingers, 4×2=8

5 Adding 40+8=48.

At last we...

No.396 21/04/25 12:36
燻し銀三 ( 60代 ♂ IJ7P0b )

【A way of changing both our hands into an electronic calculator】

《Having command of multiplication by counting numbers on fingers》

At last we reach the answer. If trying to express with letters, we may have felt roundabout so much, but doing it with our fingers actually several times, we’ll learn to find its answer more quickly, the author said like that.

To tell the truth, I’ve never heard of the way of calculation until now, so I’ve never tried it. The author continued.

It's limited to multiplications of which number is bigger than 5.

The people long long ago who didn’t learn the...

No.397 21/04/25 21:10
燻し銀三 ( 60代 ♂ IJ7P0b )

【A way of changing both of our hands into a electric calculator】

《Having command of multiplication by counting numbers on our fingers》

The people long long ago when they didn’t learn to understand the multiplication table, they thought of the multiplication by small number each other like 2×4, they regarded as addition of 2 four times, 2+2+2+2=8

But as to 8×6, when trying to think it of addition of 8 six times, they tend to get a little confused, so they contrived that way, the author said like that.

As to the multiplication table for 9, we can find its answer more easily.

No.398 21/04/25 21:31
燻し銀三 ( 60代 ♂ IJ7P0b )

【A way of changing both of our hands into an electronic calculator】

《Having command of multiplication by counting numbers on fingers》

I’m going to show the way on 9×3.

1 We spread out our both palms and direct them toward ourselves.

2 As it 9×3, we bend the middle finger alone in the left hand.

3 The left side of the two fingers from the bending middle finger is the second digit, so it’s two. The other fingers from the bending middle fingers are the first digit, so it’s 7, so it’s answer is 27.

Though it’s answer is correct, to my sorrow,I don’t understand why it is. I find it strange.

No.399 21/04/25 21:51
燻し銀三 ( 60代 ♂ IJ7P0b )

【A way of changing both of our hands into an electronic calculator】

《What should we do so as to decrease the people who are poor at math?》

Needless to say its remarks aren’t from me but from the author who teaches math, and he said like the next.

If making students calculate a multiplication of both three digits, or dividing some number on fourth digit by other number on two digit by writing, he doesn’t think it’s so significant, from the situation in which he teaches math for students in junior high school or high school or grown ups.

If the students solved questions in which that kind...

No.400 21/04/25 22:04
燻し銀三 ( 60代 ♂ IJ7P0b )

【A way of changing both of our hands into an electronic calculator】

《What should we do in order to decrease the people who think they are poor at math?》

When students solved the question in which that kind of calculations were included, he made it rule to tell them to use the electronic calculator, or saying the way of thinking is all right with it, so go ahead from that, for he wanted students to spend their time on solving other problem rather than the calculation.

But students who are good at an applied question in which they need an ability of thinking have an ability of calculation...

投稿順
新着順
主のみ
付箋

新しいレスの受付は終了しました

前スレ・次スレ

ふとした疑問掲示板のスレ一覧

ふとした疑問、普段気になっていたことなどをみんなで話そう❗

  • レス新
  • 人気
  • スレ新
  • レス少
新しくスレを作成する

サブ掲示板

注目の話題

カテゴリ一覧