# What is 4?

What is number 4? 4 (four) is a digit, numeral, and number. It’s the natural number that comes after 3 and before 5. In many East Asian societies, it is considered unlucky because it is the smallest composite number.

## What is the number 4?

4 (four) is a digit, numeral, and number. It’s the natural number that comes after 3 and before 5. In many East Asian societies, it is considered unlucky because it is the smallest composite number.

• Duodecimal: 412

• Ternary: 113

• Octal: 48

## Fourth number

The number 4 denotes a quantity or value of four in mathematics. The number 4 is the sum of the numbers 3 and 5. The name for the number four is four.

• The number four is a natural number.

• The number four is an even number.

• The number 4 is composite.

• The number 4 is the only one whose number name “four” has the same amount of letters as the number itself.

## 4

4 (four) is a digit, numeral, and number. It’s the natural number that comes after 3 and before 5. In many East Asian societies, it is considered unlucky because it is the smallest composite number.

Four is the lowest composite number in mathematics, with proper divisors of 1 and 2. The only even number in this form is 4, which is the lowest squared prime (p2). 4 is also the only prime number that is square.

If the last two digits of a number are a multiple of four, the number is a multiple of four. For example, 1092 is a multiple of 4 because 4 × 23 =92

Furthermore, 2 + 2 = 2 × 2 = 22 = 4 Using Knuth’s up-arrow notation as a guide, 2 ↑↑ 2 = 2 ↑↑↑ 2 = 4, and so on, for any number of up arrows. (For every positive integer n, 2 [n] 2 = 4, where a [n] b is the hyperoperation.)

A quadrilateral (quadrangle), sometimes known as a tetragon, is a four-sided plane shape. It’s further divided into rectangles, oblongs, squares, kites, and rhombuses.

A tetrahedron is a solid shape having four faces and four vertices, and four is the fewest number of faces (and vertices) that a polyhedron can have. A tetrahedron, also known as a 3-simplex, is a polygon with four triangular faces and four vertices. It is the only regular polyhedron that is self-dual.

The highest-dimensional space with more than three convex regular figures is four-dimensional:

• Two-dimensional: there are an endless number of convex regular polygons.

• Five convex regular polyhedra in three dimensions (the five Platonic solids).

• Six convex regular polychora in four dimensions.

• Three regular convex polytopes in five dimensions and every higher dimension (regular simplexes, hypercubes, cross-polytopes).

Differential manifolds in four dimensions offer certain unique characteristics. There is only one differential structure on {\displaystyle \mathbb {R} ^{n}}\mathbb {R} ^{n} except when n = 4, in which case there are uncountably many.

The Klein four-group is the smallest non-cyclic group with four elements. The order of the smallest non-trivial non-simple groups is similarly four. The (non-trivial) alternating group is not easy for the integer n of four. According to Ferdinand Georg Frobenius’s theorem, the maximum number of dimensions of real associative division algebra (the quaternions) is four.

According to the four-color theorem, a planar graph (or, equivalently, a flat map of two-dimensional regions such as countries) can be colored with four colors, with adjacent vertices (or regions) always being different colors. In most cases, three colors are insufficient to ensure this. There are four vertices in the largest planar complete graph.

Every positive integer can be expressed as the sum of at most four square integers, according to Lagrange’s four-square theorem. Three isn’t always enough; 7 can’t be expressed as the sum of three squares, for example.

Each natural number divisible by four is the difference between two natural numbers’ squares, i.e. 4x = y2 z2. The highest degree general polynomial equation with a radical solution is number four.

## Summary

4 (four) is a digit, numeral, and number. It’s the natural number that comes after 3 and before 5. In many East Asian societies, it is considered unlucky because it is the smallest composite number. The name for the number 4 is four. Differential manifolds in four dimensions offer certain unique characteristics. The order of the smallest non-trivial non-simple groups is similarly four.

## List of basic calculations

Multiplication 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 50 100 1000
4 × x 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 80 84 88 92 96 100 200 400 4000
Division 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
4 ÷ x 4 2 1.3 1 0.8 0.6 0.571428 0.5 0.4 0.4 0.36 0.3 0.307692 0.285714 0.26 0.25
x ÷ 4 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 2.75 3 3.25 3.5 3.75 4
Exponentiation 1 2 3 4 5 6 7 8 9 10 11 12 13
4x 4 16 64 256 1024 4096 16384 65536 262144 1048576 4194304 16777216 67108864
x 4 1 16 81 256 625 1296 2401 4096 6561 10000 14641 20736 28561

### The Arabic digit’s evolution

With the same number of lines, Brahmic numerals signified 1, 2, and 3. The number 4 was made easier by combining its four lines into a cross that resembles the contemporary plus sign. The Shunga would add a horizontal line to the digit, and the Kshatrapa and Pallava would evolve the digit to the point where writing speed was no longer an issue.

The Arabs’ 4 retained the early concept of the cross, but connected the “western” end to the “northern” end in one stroke for efficiency’s sake; the “eastern” end was completed off with a curve. The Europeans eliminated the finishing curve and gradually reduced the cursiveness of the digit, resulting in a digit that was quite similar to the original Brahmin cross.

In most modern typefaces, the shape of the character for digit 4 has an ascender, although, in typefaces containing text figures, the glyph frequently has a descender. 4 appear with an open-top on the seven-segment displays of pocket calculators and digital watches, as well as certain optical character recognition fonts.

Channel 4 television stations have used a different variant of the “open 4” from time to time, with the open portion on the side rather than the top. This variant resembles the syllabics letter of the Canadian Aboriginal people. This type of “4” is also used in the “CMC-7” font for magnetic ink character recognition.

### The Square Root Of 4

The square root of 4 is represented by the symbol 4, where the sign " is the square root symbol. The fourth number is a perfect square. As a result, finding the root of 4 and other perfect numbers is simple. In the case of a non-perfect square integer, we must apply the long division method to determine its root value.

Root 4 has a value of exactly two. However, the roots might be positive or negative, so we can say that any given number has two roots. As a result, root 4 equals 2 or +2 and -2. (positive 2 and negative 2).

A calculator can also be used to find square roots. To find the square root of a number using an online calculator, go to Square root calculator. A square number is defined as a number that is multiplied by itself. For instance, 3 × 3 = 9, making 9 a square number.

More examples can be seen below:

• 16 = 4 x 4 = 42

• 64 = 8 x 8 = 82

• 49 = 7 x 7 = 72

• 36 = 6 x 6 = 62

You will learn how to find the root of 4 in this post. This topic is covered extensively in the Class 8 syllabus, where the square and the square root of various values are calculated. Let’s go over some square root fundamentals.

### What is the definition of a perfect square?

A simple technique to determine whether a number is a perfect square or not is to use the following formula:

• A number is not a perfect square if it ends in 2, 3, 7, or 8 at the unit position.

• If a number is a perfect square, it finishes in the unit position with 1, 4, 5, 6, 9, but not the other way around. For instance, 25 is a perfect square, but 35 isn’t.

## Summary

The Europeans eliminated the finishing curve and reduced the cursiveness of the digit. The square root of 4 is represented by the symbol 4, where the sign is the square root symbol. Squaring a number is not difficult in mathematics because the calculation is simple. Find the square root of a number by first determining the original number that has been squared. It’s known as the principal square root, and it’s symbolized by the letter a.

## The square root of 40

The square root of 40 is a multiple of four and ten. We already know that the root of 4 is 2, but what about the number 10? We must use the long division method to discover the root of 10 because it is not a perfect square.

As a result, we can write,

• Value of root 40 = √40 = √4 x √10 = 2 √10

• Since, √10 = 3.162 [By long division method]

• Hence, √40 = 2 x 3.162 = 6.324

## Square root of 400

When the number four is multiplied by one hundred, the result is 400, as in 4 x 100 = 400. As you can see, both 4 and 100 are the perfect squares. Hence, it is easy to find the root value of 400. Therefore,

• √400 = √4 x √100 = 2 x 10 = 20

• Hence, 20 is the answer.

### What does the number 4 mean in math?

To multiply all whole numbers from our chosen number down to 1 Example: 4 = 4 × 3 × 2 × 1 = 24.

### What is the meaning of 4 in math?

Example: 4 is shorthand for 4 × 3 × 2 × 1. The factorial function (symbol: !) says to multiply all whole numbers from our chosen number down to 1.

### What does this symbol mean in math?

This symbol > means greater than for example 4 > 2. ≤ ≥. These symbols mean ‘less than or equal to’ and ‘greater than or equal to’ and are commonly used in algebra.

### What is the value of the number 0?

0 (zero) is a numerical digit that is used to denote a number in numerals. It is important in mathematics because it is the additive identity of integers, real numbers, and a variety of other algebraic structures.

### What is the smallest number?

“A distinct object” is what a “little number” denotes. “She’s a hot little number,” I hear (not often enough). That is to say, this girl is a hottie. So, in this case, he’s saying that this particular bottle of wine is a particularly nice bottle of wine… that is, this wine is a cheeky little number.

### Is the number 4 an angel number?

The energies of the Archangels likewise resonate with the number 4. Angel Number 4 indicates that your angels are providing you with love, support, encouragement, and inner strength, allowing you to do what you need to do and achieve your objectives with diligence and proficiency.

### Is 4 a sacred number?

In the Bible, the number four represents completion. The New Jerusalem is said to have four sides in the Bible because it signifies the new earth that is to come. In the Book of Revelations, the Bible mentions the globe having four corners, as well as four rivers flowing out of the Garden of ■■■■■■.

## What does the number 4 with a 2 mean?

4x4 is the square of four. A Square is represented by a mathematical sign. A little 2 is placed to the upper right of a number to denote that it is squared. As an example: These symbols stand for “3 squared, 4 squared, and x squared,” respectively.

## What is the 4 to the 3rd power?

The exponent, also known as the power of a number, indicates how many times it has been multiplied by itself.

Answer: The value of 4 to the 3rd power i.e., 43 is 64.

Let us calculate the value of 4 to the 3rd power i.e., 43.

### Explanation:

According to the power rule of exponents,

• am = a × a × a… m times

• Thus, 43 can be written as 4 × 4 × 4 = 64.

• Thus, the value of 4 to the 3rd power i.e., 43 is 64.

## Summary

The square root of 40 is a multiple of four and ten. When the number four is multiplied by one hundred, the result is 400. The factorial function (symbol: !) says to multiply all whole numbers from our chosen number down to 1. It is important in mathematics because it is the additive identity of integers, real numbers, and other structures. 4x4 is the square of four. The value of 4 to the 3rd power i.e., 43 is 64.

## 4 In religion

### Buddhism

• In Buddhism, there are four noble truths: Dukkha, Samudaya, Nirodha, and Magga.

• Four sights an old man, a sick man, a ■■■■ man, and an ascetic affected Prince Siddhartha severely and helped him comprehend the miseries of all beings, compelling him to embark on his spiritual quest.

• Earth, water, fire, and wind are the four great elements.

• There are Four Heavenly Kings

• Four Foundations of Mindfulness: body contemplation, feelings contemplation, mind contemplation, and mental object contemplation

• Four Effective Exertions

• Four Power Bases

• There are four jhānas

• There are four arūpajhānas

• Love, compassion, sympathetic delight, and equanimity are the four Divine Abidings.

• Enlightenment is divided into four stages: stream-enterer, once-returner, non-returner, and arahant.

• Lumbini, Bodh Gaya, Sarnath, and ■■■■■■■■ are the four principal pilgrimage sites.

### Symbolism in the Judeo-Christian faith

• God’s four-letter name is the Tetragrammaton.

• Ezekiel sees four living things in his vision: a man, a lion, an ox, and an eagle.

• Sarah, Rebekah, Leah, and Rachel are the four Matriarchs (foremothers) of Judaism.

• On the Jewish festival of Sukkot, one of the mitzvot is to use the Four Species (lulav, hadass, aravah, and etrog). (Judaism)

• The Passover wine is served in four cups on the Jewish holiday of Passover. (Judaism)

• The Four Questions to Ask on Passover, a Jewish holiday. (Judaism)

• The Four Sons will be dealt with during the Jewish Passover holiday. (Judaism)

• The Four Expressions of Redemption will be recited throughout the Jewish Passover holiday. (Judaism)

• Matthew, Mark, Luke, and John are the four Gospels. (Christianity)

• In the Book of Revelation, the Four Horsemen of the Apocalypse ride. (Christianity)

• Jerusalem, Hebron, Safed, and Tiberius are the four sacred cities of Judaism.

## Hinduism

• There are four Vedas in Hinduism: the Rigveda, Samaveda, Yajurveda, and Atharvaveda.

• Dharma, Artha, Kāma, and Moksha are the four goals of human life in Pururtha.

• Brahmacharya (student life), Grihastha (home life), Vanaprastha (retired life), and Sannyasa (monastic life) are the four stages of existence (renunciation).

• Brahmana (priest/teacher), Kshatriya (warrior/politician), Vaishya (landowner/entrepreneur), and Shudra (servant/manual laborer) are the four basic castes or strata of society.

• The swastika symbol has been employed as a sign of good luck in Hindu religions for centuries, and it represents good fortune from all four directions.

• Brahma is a four-faced god.

• Satya, Dvapara, Treta, and Kali are the four yugas.

### Islam

• Eid al-Adha takes place from the 10th to the 14th of Dhul Hajj and lasts four days.

• Islam’s four holiest cities are Mecca, Medina, Jerusalem, and Damascus.

• Muhammad, Abu Bakr, Umar ibn Khattab, and Isa ibn Maryam have tombs in the Green Dome (Jesus).

• Abu Bakr, Umar ibn al-Khattab, Uthman ibn Affan, and Ali ibn Abi Talib are the four Rashidun or Rightly Guided Caliphs.

• Jibraeel (Gabriel), Mikaeel (Michael), Izrael (Azrael), and Israfil are the Four Arch Angels in Islam (Raphael)

• Muharram, Rajab, Dhu al-Qi’dah, and Dhu al-Hijjah are the four months during which no fighting is permitted.

• Sunni fiqh is divided into four schools: Hanafi, Shafi’i, Maliki, and Hanbali.

• Abū Ḥanīfa, Muhammad ibn Idris ash-Shafi`i, Malik ibn Anas and Ahmad ibn Hanbal are four major Sunni Imams.

• In Islam, there are four books: Taurait, Zaboor, Injeel, and the Quran.

• Those who take an oath of abstention from their wives are required to wait four months, while those whose husbands die must wait four months and ten days.

• When Abraham said to Allah, “My Lord, show me how You bring the ■■■■ back to life,” Allah replied, “Why!” “Are you devoid of faith?” “Yes,” Abraham said, “but only so that my heart may be at ease.” “Then tame four birds for yourself, then put a part of them on every hill and summon them; they will come soaring to you,” he added. [2:260] Al-Baqara

• A four-month reprieve was provided to the mushriks in Surah At-Tawba so that they might thoroughly contemplate their position and determine whether to prepare for battle, depart from the nation, or adopt Islam.

• Those who accuse noblewomen of unchastity but fail to present four witnesses, flog them with eighty lashes, and refuse to acknowledge their testimony for the rest of their lives. They are, without a doubt, transgressors. [24:4 in An-Noor]

### Taoism

Four Symbols of I Ching.

### Other

• In a broader sense, many mythical and cosmogonical systems regard the four corners of the world to be roughly equivalent to the four points of the compass.

• The Zia, an indigenous tribe in the United States state of New Mexico, considers four to be a sacred number.

• Because the number four is a homonym for “death” in their languages, the Chinese, Koreans, and Japanese are superstitious about it.

• Svetovid, the god of Slavic mythology, has four heads.

## Summary

In Buddhism, there are four noble truths: Dukkha, Samudaya, Nirodha, and Magga. In the Judeo-Christian faith, Ezekiel sees four living things; Sarah, Rebekah, Leah, and Rachel are the four Matriarchs (foremothers) of Judaism. There are four major Sunni Imams: Abū Ḥanāfa, Muhammad ibn Idris ash-Shafi’i, Malik ibn Anas and Ahmad ibn Hanbal. Those who take an oath of abstention from their wives are required to wait four months.

### In politics

• Four Freedoms: Franklin D. Roosevelt declared four fundamental freedoms that should be enjoyed by everyone in the world: Freedom of expression, freedom of religion, freedom from want, and freedom from fear are all-important rights.

• Gang of Four: A popular term for four Chinese Communist Party officials who rose to prominence during China’s Cultural Revolution but were deposed after Chairman Mao Zedong’s death in 1976. Jiang Qing, Mao’s widow, was one of the four. Many more political factions led by four people have been dubbed “Gangs of Four” since then.

### In computing

In computing, a nibble is a group of four bits (half a byte).

### In science

A tetramer is an oligomer made up of four subunits in science.

### In astronomy

• Mercury, Venus, Earth, and Mars are the four terrestrial (or rocky) planets in the Solar System.

• Jupiter, Saturn, Uranus, and Neptune are the Solar System’s four big gas/ice planets.

• With a hobby telescope, four of Jupiter’s moons (the Galilean moons) are easily visible from Earth.

• In the Yerkes spectral categorization scheme, the Roman numeral IV stands for subgiant.

• Messier object M4 is a magnitude 7.5 globular cluster in the constellation Scorpius.

## In biology

• Adenine, guanine, cytosine, and thymine are the four nucleobase types found in DNA and RNA (uracil in RNA).

• Many chordates have four feet, legs, or appendages that resemble legs (tetrapods).

• The heart of a mammalian has four chambers.

• Many mammals (Carnivora, Ungulata) move with four fingers.

• All insects with wings have four wings, except flies and a few others.

• Insects of the superorder Endopterygota, often known as Holometabola, such as butterflies, ants, bees, beetles, fleas, flies, moths, and wasps, go through holometabolism in four stages: (1) embryo (■■■■, egg), (2) larva (grub, caterpillar), (3) pupa (chrysalis), and lastly (4) imago.

• The ■■■ blood group system has four blood types (A, B, O, and AB).

• Humans have four canines and four wisdom teeth.

• The cow’s stomach is divided into four digestive compartments: reticulum, rumen, omasum, and abomasum.

### In chemistry

• Carbon (the basis of life on Earth) has a valency of four in chemistry. Diamond (one of the natural allotropes of carbon) is also the hardest known naturally occurring substance due to its tetrahedral crystal bond structure. It’s also the valence of silicon, whose compounds make up the vast majority of the Earth’s crust’s mass.

• The beryllium atomic number

• Matter exists in four basic states: solid, liquid, gas, and plasma.

### In Physics

• Special and general relativity in physics treat nature as four-dimensional: The treatment of three-dimensional regular space and one-dimensional time is referred to as spacetime. A light cone is constituted of four zones of probable communication and cause and effect exist for any event E. (outside the light cone is strictly incommunicado).
• There are four basic factors at work (electromagnetism, gravitation, the weak nuclear force, and the strong nuclear force).
• The four functions inequality is a statistical mechanics inequality for four functions on a finite distributive lattice.

### In technology

• 4 is a resin identifying code that is used in recycling.

• A resin identification code that is used to identify low-density polyethylene in recycling.

• Tables, chairs, and other pieces of furniture usually have four legs.

• Printing is done using the four-color method (CMYK).

• Rectangles (with four angles and four sides) are frequently used because of their effective form and ability to be placed near together (houses, rooms, tables, bricks, sheets of paper, screens, film frames).

• Language code 4 in the Rich Text Format specification refers to the Chinese language. The codes for regional Chinese varieties are all 4 mod 256.

• Fourteen function keys are found on credit card machines.

• The 4 key on most phones corresponds to the letters G, H, and I,[86], but on the BlackBerry cellular phone, it corresponds to the letters D and F.

• If the shift key is held down, the “4” key can also be used to type the dollar sign (\$) on many computer keyboards.

• It refers to the number of bits in a nibble, which is half a byte.

• The word “for” can be replaced with “4” in online slang (as “four” and “for” are pronounced similarly). Typing “4u” instead of “for you” is an example.

### In transport

• Many internal combustion engines are referred to as four-stroke engines because they complete one thermodynamic cycle in four steps: intake, compression, power, and exhaust.

• Most vehicles, especially motor vehicles, have four road wheels, particularly cars/automobiles and light commercial vehicles.

• The word “Quattro,” which means “four” in Italian, is used by Audi as a trademark to denote that Audi-branded vehicles feature all-wheel drive (AWD) technologies.

• [89] Audi coined the term “Quattro” in 1980 to describe their first four-wheel-drive coupé, the Audi Quattro. Quattro GmbH, an Audi subsidiary, is a privately held firm.

• A list of highways with the number 4

### In other fields

• For four years, the international marine signal flag was flown.

• Many swear words in the English language are referred to as “four-letter terms.”

• The number four is the only one whose name has the same number of letters as its value in English.

• The number four (, pinyin s) is regarded as unfortunate in Chinese, Korean, Vietnamese, and Japanese cultures, primarily in Eastern Asia, since it sounds like “death” (, pinyin s). Many numbered product lines omit the “four” to avoid complaints from those with tetraphobia: for example, Nokia mobile phones (there was no series beginning with a 4 until the Nokia 4.2), Palm PDAs, and so on. In largely Asian neighborhoods, some structures skip floor 4 or replace the number with the letter “F.”

• The number 4 denotes security and stability in Pythagorean numerology (a pseudoscience).

• The number of characters in a four-character canonical phrase.

• The numeral 4 is referred to as “fower” in the NATO phonetic alphabet.

• Cancer is the fourth zodiac sign, according to astrology.

• The Emperor is the fourth trump or Major Arcana card in the Tarot deck.

• In Tetris, a game named after the Greek word for four, each shape is made up of four bricks.

• At the current size of the Supreme Court, 4 reflects the number of Justices required to grant a writ of certiorari (i.e., consent to hearing a case; it is one less than the number required to render a majority decision).

• Number Four is a character in the Lorien Legacies book series.

• The fourth wall is an imaginary barrier that separates the audience from the artists in the performing arts, and it is “broken” when performers communicate directly with the audience.

## FAQ’s

### 1. What is the meaning of 4 in math?

The number 4 denotes a quantity or value of four in mathematics. The number 4 is the sum of the numbers 3 and 5. The name for the number four is four.

### 2. Why is the number 4 special?

The four elements of earth, air, fire, and water; the four seasons; the four points of the compass; and the four phases of the Moon make up the number four in the cosmos (new, half-moon waxing, full, half-moon waning). The Four Noble Truths are the essence of Buddhism.

### 3. What is the word for 4?

A group or unit of four people or things is called a quartet ■■■■■■■■ and quad quadruplet.

### 4. What does angel number 444 mean?

In essence, the number 444 is an angel number that indicates that you are in love and that your inner wisdom has been guiding you on the correct route. The number 444 represents love and completeness. This number indicates that you are enamored with every aspect of your being.

### 5. Is number 4 a lucky number?

The numbers 3, 5, and 8 are regarded as lucky, whereas the number 4 is considered unlucky. These customs are not exclusive to Chinese culture; other cultures with a history of Han characters have comparable beliefs based on these characters.

### 6. What does 4 mean in love?

Your guardian angels are sending you a message to remind you of their love and support, and the number 4 is one of them. Just because you’re seeing angel number 4 at this time doesn’t imply it happened by chance.

### 7. Is 4 a good number?

(四->Sì) is how the number four is pronounced. The term meaning death, on the other hand, is pronounced (死->Sǐ). The number four is thought to represent bad luck and death because both terms have similar pronunciations. The number four, on the other hand, might be regarded as prosperous and lucky!

### 8. Is 4 a holy number?

The Zia, an indigenous tribe in the United States state of New Mexico, considers four to be a sacred number. Because the number four is a homonym for “death” in their languages, the Chinese, Koreans, and Japanese are superstitious about it. Svetovid, the god of Slavic mythology, has four heads.

### 9. What is life path number 4?

Personality is the fourth life path.

By nature, people with the Life Path Number 4 are practical, sensible, pragmatic, and rational. Apart from being effective, they are highly meticulous and well-ordered. It implies that individuals use a sensible reasoning process when making life decisions.

### 10. In the Bible, what is 444?

In the Bible, the number 444 is a symbol of change, truth, and personal character, therefore this could be seen as a response to your heart’s aspirations. With all of this in mind, you may presume that you should be prepared for a shift shortly.

## Conclusion

4 (four) is a digit, numeral, and number. It’s the natural number that comes after 3 and before 5. In many East Asian societies, it is considered unlucky because it is the smallest composite number. Differential manifolds in four dimensions offer certain unique characteristics. The order of the smallest non-trivial non-simple groups is similarly four. The Europeans eliminated the finishing curve and reduced the cursiveness of the digit. The square root of 4 is represented by the symbol 4, where the sign is the square root symbol. It is important in mathematics because it is the additive identity of integers, real numbers, and other structures.