25

Quarter is 25 percent of something. And this word in includes various meanings, for noun, verb and others.

One is the place, a part of some squared land. The origin of this use may be that the word quarter was used as the unit to express certain length.

24

1x1+2x2+3x3...+24x24=70x70 is a perfect square.

23

A prime number is a natural number that has exactly two distinct natural number divisors: 1 and itself. The smallest twenty-five prime numbers (all the prime numbers under 100) are:

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97.

The sum of the first 23 primes is 874, which is divisible by 23, a property shared by few other numbers.

22

It is frequently the day of the Autumnal Equinox in the Northern Hemisphere, and the Vernal Equinox in the Southern Hemisphere.

21

March 21st is the common date of the March equinox (although astronomically the equinox is more likely to fall on March 20 in all but the most easterly longitudes). In astrology, the day of the equinox is the first full day of the sign of Aries. It is also the traditional first day of the astrological year.

20

The Rubik's Cube is a 3-D mechanical puzzle invented in 1974 by Hungarian sculptor and professor of architecture Ern Rubik.

20 is the number of quarter or half turns required to optimally solve a Rubik's cube in the worst case, also known as God's number.

19

19 is the command in Age of Empires for the laughing emote. This was an easier way to laugh before "LOL" existed.

17

17, this is the number of syllables in a haiku (5+7+5).

16

In the computer, information is managed with digital information, 0 and 1.

But for some parts, in order to express the information in short expression, hexadecimal is adopted.

Hexadecimal system uses 0 to 9 and A to F for expressing numbers. This is commonly used in the memory of computers.

2.718281828

The natural logarithm can be defined for all positive real numbers a as the area under the curve y = 1/x from 1 to a.

This number is irrational, and approximated to 2.718281828...

As already described in the topic of Pi, there is a connection between Pi and natural logarithm. This is because that natural logarithm is utilized for expressing complex number and a vector on the plate by polar form.

15

Fifteen is the magic constant of the unique order-3 normal magic square:

In recreational mathematics, a magic square of order n is an arrangement of n-square numbers, usually distinct integers, in a square, such that the n numbers in all rows, all columns, and both diagonals sum to the same constant. A normal magic square contains the integers from 1 to n-square.

Magic square is well known in Japan as the puzzle "Sudoku".

14

Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure free element in nature. It is more widely distributed in dusts, sands, planetoids and planets as various forms of silicon dioxide (silica) or silicates. In Earth's crust, silicon is the second most abundant element after oxygen, making up 27.7% of the crust by mass.

And yes, the atomic number of silicon is 14.

13

A Pythagorean triple consists of three positive integers a, b, and c, such that a x a + b x b = c x c. Such a triple is commonly written (a, b, c), and a well-known example is (3, 4, 5). If (a, b, c) is a Pythagorean triple, then so is (ka, kb, kc) for any positive integer k. A primitive Pythagorean triple (PPT) is one in which a, b and c are pairwise coprime. A right triangle whose sides form a Pythagorean triple is called a Pythagorean triangle.

13 forms one of the Pythagorean triangle; 5 x 5 + 12 x 12 = 13 x 13.

Twelve

The word "twelve" is a native English word that presumably arises from the Germanic compound twa-lif "two-leave", meaning that two is left after one takes away the base, ten. This compound meaning may have been transparent to speakers of Old English, but the modern form "twelve" is quite opaque. Only the remaining tw- hints that twelve and two are related. Etymology (Weekley, Skeat) suggests that "twelve" (similar to "eleven") consists of two parts, the first meaning "two" and the second "leftover", so a literal translation would yield "two remaining [after having ten taken]".

Eleven

If a number is divisible by 11, reversing its digits will result in another multiple of 11. As long as no two adjacent digits of a number added together exceed 9, then multiplying the number by 11, reversing the digits of the product, and dividing that new number by 11, will yield a number that is the reverse of the original number.

For example:
12 x 11 = 132.
231 / 11 = 21.

Or

142,312 x 11 = 1,565,432. 2,345,651 / 11 = 213,241.

So amazing calculation.

0.0123456789

There is a number called "recurring decimals", which is the division of two integers and the calculation result is infinite decimal expansion ending.

0.0123456789012.., this repeats 0123456789. This is the calculation result of 1/81. One of the most beautiful recurring decimals

10

The decimal numeral system has ten as its base. It is the numerical base most widely used by modern civilizations.

It is said that decimal numeral system started in China, BC 13th century. At that time, they have no numbers, and they have used rods, made with bamboo or wood colored with black, for counting.

Archaeological evidence indicated that a full-fledged, positional decimal system of numerals, known as the rod calculus, consisting of "hardware" (the counting rods) and "software" (Chinese multiplication table) with the associated arithmetic operations of addition, subtraction, multiplication and division was fully developed in theSpring and Autumn period.

9.81

9.81, this is the gravitational acceleration factor on the Earth.

This means that, ignoring air resistance, an object falling freely near the Earth's surface increases its velocity by 9.81 m/s (32.2 ft/s or 22 mph) for each second of its descent.

But there is air resistance in actual world, so the velocity becomes constant value when the air resistance becomes equivalent to gravity; F = mg, m is the mass of the object, and F is the skin friction or interface drag.

Eight

The prefix "octo-" means eight in Latin. For instance, octopus is named because of eight legs.

But the name of the month October is the 10th month in the year. So wondering thing.

This is because the origin of the name of months in Gregorian calendar. Originally, the Roman calendar includes just 10 months; Martius, Aprilis, Maius, Iunius, Quintilis, Sextilis, September, October, November, December.

These calendar included 304 day and there were 61 days not assigned to any month.

After some reform, adding a month and splitting it, the months became 12.

Additionally, The eighth month is named August, because of the name of Augustinus.

6.02214179

6.02214179(30)×10^23

This is the number known as Avogadro factor. The Avogadro constant expresses the number of elementary entities per mole of substance.

The Avogadro constant is named after the early nineteenth century Italian scientist Amedeo Avogadro, who, in 1811, first proposed that the volume of a gas (at a given pressure and temperature) is proportional to the number of atoms or molecules regardless of the nature of the gas.

Seven

Seven, a very cabalistic and used number through history, is considered as lucky number among other reasons for being the number of perfection.

God, the Bible says, created the Universe in 7 days. Thus 6 is the imperfect number, this is why 666 is the number of Satan or the Beast.

On dices, where seven is a winning number, to get a 7 you need one dice on 6 and a 1 on the opposite side on the other dice. All opposite side numbers adds to 7.

Six

Six sigma is very famous concept invented in GE.

In this concept, the business process is elaborated aiming at the higher quality; sigma is the variance in statistics, and six sigma is that the quality is as high as the probability that the sample included to the rejection region, μ±6σ, is 3.4/1,000,000.

But actually, assuming the normalized distribution, the probability above is 2/1,000,000,000. This is because of the basic assumption for six sigma is the idea related the User Specification Limit, the concept of industry.

27

Honorificabilitudinitatibus, one of the longest words in English. This word appears in the masterpiece of Shakespeare.

The length of this word is 27.

Five

There are various pentagon in the nature, such as morning glory and sea star. The reason why these plants and animals are formed to be pentagon may be the stability, like triangle.

As you know, US Headquarter of Department of Defense is called the pentagon, after the shape of building.

Below is the drawing method for pentagon, very interesting;

Draw a circle in which to inscribe the pentagon and mark the center point O. (This is the green circle in the diagram to the right).
Choose a point A on the circle that will serve as one vertex of the pentagon. Draw a line through O and A.
Construct a line perpendicular to the line OA passing through O. Mark its intersection with one side of the circle as the point B.
Construct the point C as the midpoint of O and B.
Draw a circle centered at C through the point A. Mark its intersection with the line OB (inside the original circle) as the point D.
Draw a circle centered at A through the point D. Mark its intersections with the original (green) circle as the points E and F.
Draw a circle centered at E through the point A. Mark its other intersection with the original circle as the point G.
Draw a circle centered at F through the point A. Mark its other intersection with the original circle as the point H.

Four

Square is artificial shape in the nature. And the right corner and kind of that is the symbol of artifacts.

These days, the products with natural materials but the shaped with squared or right corners are assumed to be cool. These products includes paradox. Most of the modern arts are consists of paradox or aufhben, that should be the element in modern arts.

i

You should say that "i" is not number, but this is actually  a number, "i" is the square root of negative number.


This number is deeply connected with complex number. Complex number distributed mathematics new possibility from the world of real numbers.

Also, "i" connect the imaginary number to real number, also this express the 2 dimensional world not using vector.

"i" is not just one thing but include so many possibilities and  potentials.

Pi

Pi is the value expressing ratio of any circle's circumference to it's diameter.
This is endless number, and there is a person who memory the longest part of this and recorded to the Guinness book. I memory that he just memory the number all the day, and everyday.
I think Pi is one of the most beautiful number in the world, because of the Euler's formula. In this formula, e^(i Pi)=-1, natural logarithm raised by Pi times i is 1 negative.
I think this formula is the most beautiful one in the world of mathematics. This express the world of real number and imaginary number.

Three

Three is assumed to be stable, balanced number, second to zero, sometimes circle as a structure.
Also, there are so many quote with 3 elements.
The shape of the Arabic number 3 was originally three lines. Writing them fluently, and the shape became like modern one.
Finally, the nearest thing but we don't care usually is that the earth is the third planet in the solar system.

0.1

0.1, zero point one, and any numbers non integer is very annoying when you program. Because all the information in the computer consists with 1 and 0. And all the numbers are expressed with 1, 2, 4, 8 and like. So when you express the number, it is approximated value. As a result, the very simple summation calculation doesn't completed; 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 doesn't equal to 1.
Very bothering phenomena in the computer under the "point".

One

Following the previous topic, today's theme is one.

One has similar specification with zero; multiplied or dividend with one, the number doesn't change.

In Roman numeral, one is expressed with the character 'I'. 'I' descends not from the letter 'I' but from a notch scored across the stick.

As a trivial episode, many older typewriters do not have a separate symbol for '1' and use the lowercase 'l' instead.

And because of this, it is possible to find cases when the uppercase 'J' is used instead, while it may be for decorative purposes.

Numbers

I want to decide the theme of this blog as Numbers.

I'd like to reveal episode related to numbers.

The first topic is zero.

Zero is the number immediately preceding one. This is the central part of every other numbers. It includes very unique specification, such as that even any number, it becomes zero multiplied with zero.

Zero is the perception that there is nothing. This is kind of philosophy, because there exists nothing with zero.

I think zero is one of the most beautiful numbers.