What is the number PI and what does it mean? How to type “hidden” characters on the keyboard using Alt codes and HTML mnemonics.

The meaning of the number "Pi", as well as its symbolism, is known all over the world. This term denotes irrational numbers (that is, their value cannot be accurately expressed as a fraction y/x, where y and x are integers) and is borrowed from the ancient Greek phraseology "perepheria", which can be translated into Russian as "circle".
The number "Pi" in mathematics denotes the ratio of the circumference of a circle to the length of its diameter. The history of the origin of the number "Pi" goes back to the distant past. Many historians have tried to establish when and by whom this symbol was invented, but they were never able to find out.

Pi" is a transcendental number, or saying in simple words it cannot be the root of some polynomial with integer coefficients. It can be designated as a real number or as an indirect number that is not algebraic.

The number "Pi" is 3.1415926535 8979323846 2643383279 5028841971 6939937510...

Pi" may not only be an irrational number that cannot be expressed using several different numbers. The number "Pi" can be represented by a certain decimal, which has an infinite number of digits after the decimal point. More interesting point- all these numbers cannot be repeated.

Pi" can be correlated with the fractional number 22/7, the so-called “triple octave” symbol. The ancient Greek priests knew this number. In addition, even ordinary residents could use it to solve any everyday problems, and also used for designing such the most complex buildings like tombs.
According to scientist and researcher Hayens, a similar number can be traced among the ruins of Stonehenge, and also found in the Mexican pyramids.

Pi" Ahmes, a famous engineer at that time, mentioned in his writings. He tried to calculate it as accurately as possible by measuring the diameter of the circle using the squares drawn inside it. Probably in some sense this number has some mystical, sacred meaning for the ancients.

Pi" is essentially the most mysterious mathematical symbol. It can be classified as delta, omega, etc. It represents a relationship that will turn out to be exactly the same, regardless of where the observer will be in the universe. In addition, it will be unchanged from the object of measurement.

Most likely, the first person who decided to calculate the number "Pi" using mathematical method is Archimedes. He decided to draw regular polygons in a circle. Considering the diameter of a circle to be one, the scientist designated the perimeter of a polygon drawn in a circle, considering the perimeter of an inscribed polygon as an upper estimate, and as a lower estimate of the circumference

What is the number "Pi"

Today we’ll talk about one remarkable feature that a fairly small number of PC users know about. This may be surprising, but I’ve already seen a lot of how, for simple copying, which is performed using the Ctrl-C key combination, people select the desired fragment (usually a word) with the mouse, then press the right key and select the “copy” option. Alternative option- copying via the button located on the toolbar.

How do you usually insert characters into text that are not explicitly listed on the keyboard? The “Symbol Table” program is called ( Win+R → charmap → Enter ), there the required symbol is searched for a long time and persistently, which is added. There is perhaps only one downside to this solution - it takes too long to search. I don’t argue that sometimes you come across truly “unprintable characters”, but usually this is not required.

To dial the Alt code, you should hold down the Alt key (are you surprised?) and on the numeric keypad (the one on the right, behind the arrows), press the indicated numbers one by one, then release the Alt key. Problems may arise with shortened keyboards, which is typical for laptops. In this case, as a rule, you need to additionally hold down the blue Fn key.

In the table below I tried to collect the most necessary symbols, supplemented by potentially useful ones. In addition to Alt codes, HTML mnemonics are also provided.

Mnemonics - a construction that encodes special characters in a certain way. Has the form: &designation; -.

ampersand+designator+semicolon There are contraindications for the arbitrary use of special characters from the table. It doesn't matter whether the symbol is printed "as is" or using mnemonics, it can only be displayed if it is presented in the font used. Otherwise, you will see a rectangle, a question mark, and something else indicating that there is no image for the specified symbol. Now this problem successfully solved thanks to plug-in fonts. But authors of texts need to keep in mind that a Word document typed in the Calibri font will not always be fully displayed by a customer who uses a different with its own set of pre-installed fonts. The “most useful symbols” can be considered safe, but problems can occur with fractions.

Explanations about the signatures “for ru” and “for en”. This is the current, active, input language. As a rule, the default switching is assigned to the Alt+Shift key combination.

Symbol	Alt+	Mnemonics	Name/purpose
Most useful symbols
-	0151	—	em dash (m-dash), for Russian the only correct spelling
«	0171	«	opening quote "herringbone"
»	0187	»	closing quotation mark "herringbone"
	0160		non-breaking space (words separated by such a space are always on the same line)
…	0133	…	ellipsis
„	0132	„	double bottom quote
“	0147	“	double left quote
”	0148	”	double right quote
‚	0130	‚	single lower quote
‘	0145	‘	single left quote
’	0146	’	single right quote
©	0169		copyright (copyright protection symbol)
™	0153	™	trademark
®	0174	®	trademark protection sign
–	0150	-	mid dash (n-dash)
"	34	"	programmer double quote
<	60	<	less sign
>	62	>	"more" sign
‘	39	"	regular single quote (located to the left of the Enter key)
&	38	&	ampersand
°	248 or 0176	°	degree sign
№	252 or 0185 (for ru)	№	number sign (Shift+3 in Russian layout)
√	251	√	Square root
·	250 0183	·	interpunct (point for dividing words in Latin writing)
¤	253 0164	¤	currency sign
€	0128 (for ru) 0136 (for en)	€	Euro symbol
¥	0165	¥	yen symbol
¢	0162	¢	cent symbol (American)
£	0163	£	pound symbol (British)
×	0215	×	multiplication sign
÷	0247	÷	division sign
−	-	−	minus sign (correct, not the same as minus hyphen)
+	43	+	plus sign
±	0177	±	plus or minus
¹	0185	¹	superscript "1"
²	0178	²	superscript "2"
³	0179	³	superscript "3"
‰	0137	‰	ppm
­	0173	-	“soft” hyphen (means that in a given place the browser, at its discretion, can hyphenate part of the word), must be identical in spelling to a hyphen, invisible to the user except in cases of word hyphenation
Arrows
	16		right
◄	17	◄	left
▲	30	▲	up
▼	31	▼	down
↕	18	↕	up down
↔	29	↔	left-right
	24		up
↓	25	↓	down
→	26	→	right
←	27	←	left
¶	20 or 0182	¶	paragraph symbol
§	21 or 0167	§	paragraph symbol
`	96	-	typewritten back apostrophe (to the left of key 1, above Tab)
Other symbols
☺	1	-	smiley
☻	2	-	inverted smiley
	3		hearts (heart)
♦	4	♦	diamonds
♣	5	♣	clubs (crosses)
♠	6	♠	peaks
	7 or 0149	.	bullet for list
♂	11	-	designation of the male gender (symbol of the planet Mars)
♀	12	-	designation of the female gender (mirror of Venus)
ƒ	0131	ƒ	Latin f with a tail
†	0134	†	cross
‡	0135	‡	double cross
¡	0161	¡	inverted exclamation point
¦	0166	¦	"ragged" vertical line
¬	0172	¬	negative sign
µ	0181	µ	symbol "micro" (used in the SI system to indicate the corresponding prefix)
Greek lowercase letters
α	-	α	alpha
β	-	β	beta
γ	-	γ	gamma
δ	-	δ	delta
ε	-	ε	epsilon
ζ	-	ζ	zeta
η	-	η	this
θ	-	θ	theta
ι	-	ι	iota
κ	-	κ	kappa
λ	-	λ	lambda
μ	-	μ	mu
ν	-	ν	nude
ξ	-	ξ	xi
ο	-	ο	omicron
π	-	π	pi
ρ	-	ρ	ro
σ	-	σ	sigma
τ	-	τ	tau
υ	-	υ	upsilon
φ	-	φ	fi
χ	-	χ	hee
ψ	-	ψ	psi
ω	-	ω	omega
Greek capital letters
Α	-	Α	alpha
Β	-	Β	beta
Γ	-	Γ	gamma
Δ	-	Δ	delta
Ε	-	Ε	epsilon
Ζ	-	Ζ	zeta
Η	-	Η	this
Θ	-	Θ	theta
Ι	-	Ι	iota
Κ	-	Κ	kappa
Λ	-	Λ	lambda
Μ	-	Μ	mu
Ν	-	Ν	nude
Ξ	-	Ξ	xi
Ο	-	Ο	omicron
Π	-	Π	pi
Ρ	-	Ρ	ro
Σ	-	Σ	sigma
Τ	-	Τ	tau
Υ	-	Υ	upsilon
Φ	-	Φ	fi
Χ	-	Χ	hee
Ψ	-	Ψ	psi
Ω	-	Ω	omega
Fractions
½	0189	½	fraction "one half"
⅓	-	⅓	fraction "one third"
¼	0188	¼	fraction "one quarter"
⅕	-	⅕	fraction "one fifth"
⅙	-	⅙	fraction "one sixth"
⅛	-	⅛	fraction "one eighth"
⅔	-	⅔	fraction "two thirds"
⅖	-	⅖	fraction "two fifths"
¾	0190	¾	fraction "three-quarters"
⅗	-	⅗	fraction "three fifths"
⅜	-	⅜	fraction "three-eighths"
⅘	-	⅘	fraction "four fifths"
⅚	-	⅚	fraction "five-sixths"
⅝	-	⅝	fraction "five-eighths"
⅞	-	⅞	fraction "seven-eighths"

When texts are replete with such “unprintable” characters, it is better to install a specialized editor that allows you to “program” the desired action for a certain key combination.

(), and it became generally accepted after the work of Euler. This designation comes from the initial letter of the Greek words περιφέρεια - circle, periphery and περίμετρος - perimeter.

Ratings

• 510 decimal places: π ≈ 3.141 592 653 589 793 238 462 643 383 279 502 884 197 169 399 375 105 820 974 944 592 307 816 406 286 208 998 628 034 825 342 117 067 982 148 086 513 282 306 647 093 844 609 550 582 231 725 359 408 128 481 117 450 284 102 701 938 521 105 559 644 622 948 954 930 381 964 428 810 975 665 933 446 12 8 475 648 233 786 783 165 271 201 909 145 648 566 923 460 348 610 454 326 648 213 393 607 260 249 141 273 724 587 006 606 315 588 174 881 520 920 962 829 254 091 715 364 367 892 590 360 011 330 530 8 820 466 521 384 146 951 941 511 609 433 057 270 365 759 591 953 092 186 117 381 932 611 793 105 118 548 074 462 379 962 749 567 351 885 752 724 891 227 938 183 011 949 129 833 673 362…

Properties

Ratios

There are many known formulas with the number π:

• Wallis formula:

• Euler's identity:

• T.n. "Poisson integral" or "Gauss integral"

Transcendence and irrationality

Unsolved problems

• It is not known whether the numbers π and e algebraically independent.
• It is unknown whether the numbers π + e , π − e , π e , π / e , π e , π π , e e transcendental.
• Until now, nothing is known about the normality of the number π; it is not even known which of the digits 0-9 appear in the decimal representation of the number π an infinite number of times.

Calculation history

and Chudnovsky

Mnemonic rules

So that we do not make mistakes, We must read correctly: Three, fourteen, fifteen, ninety-two and six. You just have to try and remember everything as it is: Three, fourteen, fifteen, ninety-two and six. Three, fourteen, fifteen, nine, two, six, five, three, five.

2. So that do science, Everyone should know this.

This I know and remember perfectly: But many signs are unnecessary for me, in vain.

Whoever, jokingly and soon, wishes Pi to know the number - already knows!

So Misha and Anyuta came running and wanted to find out the number.

(The second mnemonic is correct (with rounding of the last digit) only when using pre-reform spelling: when counting the number of letters in words, it is necessary to take into account hard signs!)

Another version of this mnemonic notation:

This I know and remember perfectly:
And many signs are unnecessary for me, in vain.
Let's trust our enormous knowledge
Those who counted the numbers of the armada.

Once at Kolya and Arina's We ripped the feather beds. The white fluff was flying and spinning, Showered, froze, Satisfied He gave it to us Old women's headache. Wow, the spirit of fluff is dangerous!

If you follow the poetic meter, you can quickly remember:

Three, fourteen, fifteen, nine two, six five, three five
Eight nine, seven and nine, three two, three eight, forty six
Two six four, three three eight, three two seven nine, five zero two
Eight eight and four, nineteen, seven, one

Fun facts

Notes

See what “Pi” is in other dictionaries:

number- Receiving source: GOST 111 90: Sheet glass. Specifications original document See also related terms: 109. The number of betatron oscillations ... Dictionary-reference book of terms of normative and technical documentation

Noun, s., used. very often Morphology: (no) what? numbers, what? number, (see) what? number, what? number, about what? about number; pl. What? numbers, (no) what? numbers, why? numbers, (see) what? numbers, what? numbers, about what? about numbers mathematics 1. By number... ... Dictionary Dmitrieva

NUMBER, numbers, plural. numbers, numbers, numbers, cf. 1. Concept, expressive quantity, that by which objects and phenomena are counted (mat.). Integer. A fractional number. Named number. Prime number. (see simple 1 in 1 value).… … Ushakov's Explanatory Dictionary

An abstract designation devoid of special content for any member of a certain series, in which this member is preceded or followed by some other specific member; abstract individual feature that distinguishes one set from... ... Philosophical Encyclopedia

Number- Number is a grammatical category expressing quantitative characteristics objects of thought. Grammatical number is one of the manifestations of the more general linguistic category of quantity (see Language category) along with the lexical manifestation (“lexical... ... Linguistic encyclopedic dictionary

A number approximately equal to 2.718, which is often found in mathematics and science. For example, during the collapse radioactive substance after time t, a portion of the initial amount of substance remains equal to e kt, where k is a number,... ... Collier's Encyclopedia

A; pl. numbers, sat, slam; Wed 1. A unit of account expressing a particular quantity. Fractional, integer, prime hours. Even, odd hours. Count in round numbers (approximately, counting in whole units or tens). Natural h. (positive integer... encyclopedic Dictionary

Wed. quantity, by count, to the question: how much? and the very sign expressing quantity, number. Without number; there is no number, without counting, many, many. Set up cutlery according to the number of guests. Roman, Arabic or church numbers. Integer, opposite. fraction... ... Dahl's Explanatory Dictionary