### 12 (number)

12twelve12th
This is not a binding rule, and in English language tradition, it is sometimes recommended to spell out numbers up to and including either nine, ten or twelve, or even ninety-nine or one hundred. Another system spells out all numbers written in one or two words (sixteen, twenty-seven, fifteen thousand, but 372 or 15,001).In German orthography, there used to be the widely followed (but unofficial) rule of spelling out numbers up to twelve (zwölf). The Duden (the German standard dictionary) mentions this rule as outdated. Twelve is a composite number, the smallest number with exactly six divisors, its divisors being 1, 2, 3, 4, 6 and 12.

### Text figures

old-style numeralsold style figuresoldstyle figures
In the most common scheme, 0, 1, and 2 are of x-height, having neither ascenders nor descenders; 6 and 8 have ascenders; and 3, 4, 5, 7, and 9 have descenders. Other schemes exist; for example, the types cut by the Didot family of punchcutters and typographers in France between the late 18th and early 19th centuries typically had an ascending 3 and 5, a form preserved in some later French typefaces. A few other typefaces used different arrangements. Sometimes the stress of the 0 is made different from a letter o in some way, although many fonts do not do this.

### 18 (number)

18eighteen18th
Eighteen is a composite number, its divisors being 1, 2, 3, 6 and 9. Three of these divisors (3, 6 and 9) add up to 18, hence 18 is a semiperfect number. Eighteen is the first inverted square-prime of the form p·q 2. * In Chinese tradition, 18 pronounced 十八 (shí bā) and is considered a lucky number due to similarity with 實發 (shì fā) 'definitely get rich', 'to get rich for sure'. In most countries, 18 is the age of majority (adulthood) and also the voting age. In eleven states of the United States, 18 is the age of sexual consent.

### 22 (number)

22Super Bowl XXII
22 (twenty-two) is the natural number following 21 and preceding 23. *22 is the atomic number of titanium. *22 is the designation of the USAF stealth fighter, the F-22 Raptor. *The number of yards in a chain. Twenty-two may also refer to: 22 is a deficient number. 22 is an even composite number and a semiprime; its proper divisors are 1, 2, and 11. 22 is a pentagonal number and a centered heptagonal number.

### 24 (number)

24number 24twenty-four
This is because among any four consecutive numbers there must be two even numbers, one of which is a multiple of four, and there must be a multiple of three. The tesseract has 24 two-dimensional faces (which are all squares). 24 is the only nontrivial solution to the cannonball problem, that is: 1 2 + 2 2 + 3 2 + … + 24 2 is a perfect square (70 2 ). (The trivial case is just 1 2 = 1 2 .). In 24 dimensions there are 24 even positive definite unimodular lattices, called the Niemeier lattices.

### Binary number

binarybinary numeral systembase 2
In the following example, two numerals are being added together: 1 1 1 0 1 1 1 1 1 0 2 (958 10 ) and 1 0 1 0 1 1 0 0 1 1 2 (691 10 ), using the traditional carry method on the left, and the long carry method on the right: Traditional Carry Method Long Carry Method vs. carry the 1 until it is one digit past the "string" below 1 1 1 0 1 1 1 1 1 0 1 1 1 0 1 1 1 1 1 0 cross out the "string", + 1 0 1 0 1 1 0 0 1 1 + 1 0 1 0 1 1 0 0 1 1 and cross out the digit that was added to it = 1 1 0 0 1 1 1 0 0 0 1 1 1 0 0 1 1 1 0 0 0 1 The top row shows the carry bits used.

### ASCII

7-bit ASCIIAmerican Standard Code for Information InterchangeASCII printable characters
Many of the non-alphanumeric characters were positioned to correspond to their shifted position on typewriters; an important subtlety is that these were based on mechanical typewriters, not electric typewriters. Mechanical typewriters followed the standard set by the Remington No. 2 (1878), the first typewriter with a shift key, and the shifted values of were early typewriters omitted 0 and 1, using O (capital letter o) and l (lowercase letter L) instead, but and pairs became standard once 0 and 1 became common. Thus, in ASCII were placed in the second stick, positions 1–5, corresponding to the digits 1–5 in the adjacent stick.

### Chinese numerals

ChineseChinese numeralChinese numeral characters
The following table lists the two different standards together with the early translation. Multiple-digit numbers are constructed using a multiplicative principle; first the digit itself (from 1 to 9), then the place (such as 10 or 100); then the next digit. In Mandarin, the multiplier (liǎng) is often used rather than (èr) for all numbers 200 and greater with the "2" numeral (although as noted earlier this varies from dialect to dialect and person to person). Use of both 兩 (liǎng) or 二 (èr) are acceptable for the number 200. When writing in the Cantonese dialect, 二 (yi 6 ) is used to represent the "2" numeral for all numbers.

### Eastern Arabic numerals

ArabicEastern ArabicUrdu
The numeral system originates from an ancient Indian numeral system, which was re-introduced in the book On the Calculation with Hindu Numerals written by the medieval-era Iranian mathematician and engineer Khwarazmi, whose name was Latinized as Algoritmi. These numbers are known as أرقام هندية ("Indian numbers") in Arabic. They are sometimes also called "Indic numerals" in English. However, that is sometimes discouraged as it can lead to confusion with Indian numerals, used in Brahmic scripts of India. Each numeral in the Persian variant has a different Unicode point even if it looks identical to the Eastern Arabic numeral counterpart.

### Hebrew numerals

HebrewgereshHebrew numeral
Gematria Chart on inner.org. Hebrew Number Chart 1 to 1 Million with English Transliteration.

### Japanese numerals

JapaneseJapanJapanese numeral
The Japanese numerals in writing are entirely based on the Chinese numerals and the grouping of large numbers follow the Chinese tradition of grouping by 10,000. Two sets of pronunciations for the numerals exist in Japanese: one is based on Sino-Japanese (on'yomi) readings of the Chinese characters and the other is based on the Japanese yamato kotoba (native words, kun'yomi readings). There are two ways of writing the numbers in Japanese: in Arabic numerals (1, 2, 3) or in Chinese numerals . The Arabic numerals are more often used in horizontal writing, and the Chinese numerals are more common in vertical writing.

### Khmer numerals

Khmer
For example, 6 is formed from 5 plus 1 . With the exception of the number 0, which stems from Sanskrit, the etymology of the Khmer numbers from 1 to 5 is of proto-Mon–Khmer origin. As mentioned above, the numbers from 6 to 9 may be constructed by adding any number between 1 and 4 to the base number 5, so that 7 is literally constructed as 5 plus 2. Beyond that, Khmer uses a decimal base, so that 14 is constructed as 10 plus 4, rather than 2 times 5 plus 4; and 16 is constructed as 10+5+1.

### Number

number systemnumericalnumeric
Gauss studied complex numbers of the form a + bi, where a and b are integral, or rational (and i is one of the two roots of x 2 + 1 = 0). His student, Gotthold Eisenstein, studied the type a + bω, where ω is a complex root of x 3 − 1 = 0. Other such classes (called cyclotomic fields) of complex numbers derive from the roots of unity x k − 1 = 0 for higher values of k. This generalization is largely due to Ernst Kummer, who also invented ideal numbers, which were expressed as geometrical entities by Felix Klein in 1893. In 1850 Victor Alexandre Puiseux took the key step of distinguishing between poles and branch points, and introduced the concept of essential singular points.

### Integer

integersintegralwhole number
This is readily demonstrated by the construction of a bijection, that is, a function that is injective and surjective from Z to N If N = 0, 1, 2, …} then consider the function: (−4,8) (−3,6) (−2,4) (−1,2) (0,0) (1,1) (2,3) (3,5) …} If N = 1, 2, 3, ...} then consider the function: {{math|{… (−4,8) (−3,6) (−2,4) (−1,2) (0,1) (1,3) (2,5) (3,7) …}}} If the domain is restricted to Z then each and every member of Z has one and only one corresponding member of N and by the definition of cardinal equality the two sets have equal cardinality. 0.999... Canonical representation of a positive integer. Hyperinteger. Integer-valued function. Integer lattice. Integer part.

### Field (mathematics)

fieldfieldsfield theory
Equivalently E is a subset of F that contains 1, and is closed under addition, multiplication, additive inverse and multiplicative inverse of a nonzero element. This means that 1 ∊ E, that for all a, b ∊ E both a + b and a · b are in E, and that for all a ≠ 0 in E, both –a and 1/a are in E Field homomorphisms are maps f: E → F between two fields such that f(e 1 + e 2 ) = f(e 1 ) + f(e 2 ) f(e 1 e 2 ) = f(e 1 )f(e 2 ), and f(1 E ) = 1 F, where e 1 and e 2 are arbitrary elements of E . All field homomorphisms are injective. If f is also surjective, it is called an isomorphism (or the fields E and F are called isomorphic).

### 3

threenumber 3
It is usually found on UPC-A barcodes and standard 52-card decks. 3 is: Three is the only prime which is one less than a perfect square. Any other number which is n − 1 for some integer n is not prime, since it is (n − 1)(n + 1). This is true for 3 as well (with n = 2), but in this case the smaller factor is 1. If n is greater than 2, both n − 1 and n + 1 are greater than 1 so their product is not prime. A natural number is divisible by three if the sum of its digits in base 10 is divisible by 3. For example, the number 21 is divisible by three (3 times 7) and the sum of its digits is 2 + 1 = 3.

### 7

seven7 (number)
Jericho's walls fall on the seventh day after seven priests with seven trumpets march around the city seven times (Joshua 6:8). King David had seven older brothers (1 Samuel 16). The child sneezed seven times after Elisha raised him from the dead (2 Kings 4:35). Seven things that are detestable to the (Proverbs 6:16–19). Seven Pillars of the House of Wisdom (Proverbs 9:1). The woman with seven sons in 2 Maccabees. Gad, whose name means good luck, is the seventh son of Jacob. Areli is the seventh son of Gad (Genesis 46:16). Chronicles lists David as the seventh son of Jesse (1 Chronicles 2:15).

### Square (algebra)

squaresquaredsquares
In other words, squaring is a monotonic function on the interval. On the negative numbers, numbers with greater absolute value have greater squares, so squaring is a monotonically decreasing function on. Hence, zero is the (global) minimum of the square function. The square x 2 of a number x is less than (that is x 2 < x ) if and only if 0 < x < 1, that is, if belongs to the open interval. This implies that the square of an integer is never less than the original number. Every positive real number is the square of exactly two numbers, one of which is strictly positive and the other of which is strictly negative. Zero is the square of only one number, itself.

### Thai numerals

Thaialternate numbersbasic numbers
It is from Sanskrit śūnya, as are the (context-driven) alternate names for numbers one to four given below; but not the counting 1 (number). Thai names for N +1 and the regular digits 2 through 9 as shown in the table, below, resemble those in Chinese varieties (e.g., Cantonese and Min Nan) as spoken in Southern China, the homeland of the overseas chinese living in South East Asia. In fact, the etymology of Thai numerals 2, 3, 4, 6, 7, 8, 9, and 10 is Middle Chinese, while the etymology of Thai numeral 5 is Old Chinese, as illustrated in the table below Numerical digit characters, however, are almost identical to Khmer numerals.

### Power of two

powers of twopower of 2powers of 2
Similarly, the number of (n − 1) -faces of an -dimensional cross-polytope is also 2 n and the formula for the number of -faces an -dimensional cross-polytope has is. The sum of the reciprocals of the powers of two is 1. The sum of the reciprocals of the squared powers of two is 1/3.

### 28 (number)

28130
It is a composite number, its proper divisors being 1, 2, 4, 7, and 14. Twenty-eight is the second perfect number. As a perfect number, it is related to the Mersenne prime 7, since 2 (3 − 1) (2 3 − 1) = 28. The next perfect number is 496, the previous being 6. Twenty-eight is the sum of the totient function for the first nine integers. Since the greatest prime factor of 28 2 + 1 = 785 is 157, which is more than 28 twice, 28 is a Størmer number. Twenty-eight is a harmonic divisor number, a happy number, a triangular number, a hexagonal number, and a centered nonagonal number. It appears in the Padovan sequence, preceded by the terms 12, 16, 21 (it is the sum of the first two of these).

### One half

half½halves
One half is the irreducible fraction resulting from dividing one by two (2) or the fraction resulting from dividing any number by its double. Multiplication by one half is equivalent to division by two, or halving; conversely, division by one half is equivalent to multiplication by two, or "doubling". One half appears often in mathematical equations, recipes, measurements, etc. Half can also be said to be one part of something divided into two equal parts.

### 0

zerozero function0 (number)
A further distinction is made in falsification-hindering typeface as used on German car number plates by slitting open the digit 0 on the upper right side. Sometimes the digit 0 is used either exclusively, or not at all, to avoid confusion altogether. In the BC calendar era, the year 1 BC is the first year before AD 1; there is not a year zero. By contrast, in astronomical year numbering, the year 1 BC is numbered 0, the year 2 BC is numbered −1, and so on. Addition: x + 0 = 0 + x = x. That is, 0 is an identity element (or neutral element) with respect to addition. Subtraction: x − 0 = x and 0 − x = −x. Multiplication: x · 0 = 0 · x = 0. Division: 0⁄x = 0, for nonzero x.

### Chinese numerology

Chinese culturenumbers in Chinese culturelucky number
In Chinese tradition, certain numbers are believed by some to be auspicious or inauspicious based on the Chinese word that the number sounds similar to. The numbers 6, 8, and 9 are generally considered to be auspicious, while 4 and 7 are considered inauspicious. The number 0 is the beginning of all things and is generally considered a good number. The number 1 is neither auspicious nor inauspicious. It is a number given to winners to indicate the first place. But it can also symbolize loneliness or being single. For example: November 11th is the Singles' Day in China, as the date has four ‘1’ which stand for singles.

### Indian numerals

Indian numeralIndian numeral systemTelugu
Devanagari digits shapes may vary depending on geographical area. The five Indian languages (Hindi, Marathi, Konkani, Nepali and Sanskrit itself) that have adapted the Devanagari script to their use also naturally employ the numeral symbols above; of course, the names for the numbers vary by language. The table below presents a listing of the symbols used in various modern Indian scripts in comparison to Western and Eastern Arabic numerals: Tamil and Malayalam also have distinct forms for numerals 10, 100, 1000 as ௰, ௱, ௲ and ൰, ൱, ൲, respectively. A decimal place system has been traced back to c. 500 in India.