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4.01.2012
4 (four) is a number, numeral and digit. It is the natural number following 3 and preceding 5. It is the smallest semiprime and composite number, and is considered unlucky in many East Asian cultures. In mathematics Four is the smallest composite number, its proper divisors being and . Four is the sum and product of two with itself: 2 + 2 = 4 = 2 x 2, the only number b such that a + a = b = a x a, which also makes four the smallest squared prime number p^. In Knuth's up-arrow notation, , and so forth, for any number of up arrows. By consequence, four is the only square one more than a prime number, specifically three. The sum of the first four prime numbers two + three + five + seven is the only sum of four consecutive prime numbers that yields an odd prime number, seventeen, which is the fourth super-prime. Four lies between the first proper pair of twin primes, three and five, which are the first two Fermat primes, like seventeen, which is the third. On ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quaternary Numeral System
A quaternary numeral system is base-. It uses the digits 0, 1, 2 and 3 to represent any real number. Conversion from binary is straightforward. Four is the largest number within the subitizing range and one of two numbers that is both a square and a highly composite number (the other being 36), making quaternary a convenient choice for a base at this scale. Despite being twice as large, its radix economy is equal to that of binary. However, it fares no better in the localization of prime numbers (the smallest better base being the primorial base six, senary). Quaternary shares with all fixed- radix numeral systems many properties, such as the ability to represent any real number with a canonical representation (almost unique) and the characteristics of the representations of rational numbers and irrational numbers. See decimal and binary for a discussion of these properties. Relation to other positional number systems Relation to binary and hexadecimal As with the o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tamil Language
Tamil (; ' , ) is a Dravidian language natively spoken by the Tamil people of South Asia. Tamil is an official language of the Indian state of Tamil Nadu, the sovereign nations of Sri Lanka and Singapore, and the Indian territory of Puducherry. Tamil is also spoken by significant minorities in the four other South Indian states of Kerala, Karnataka, Andhra Pradesh and Telangana, and the Union Territory of the Andaman and Nicobar Islands. It is also spoken by the Tamil diaspora found in many countries, including Malaysia, Myanmar, South Africa, United Kingdom, United States, Canada, Australia and Mauritius. Tamil is also natively spoken by Sri Lankan Moors. One of 22 scheduled languages in the Constitution of India, Tamil was the first to be classified as a classical language of India. Tamil is one of the longest-surviving classical languages of India.. "Tamil is one of the two longest-surviving classical languages in India" (p. 7). A. K. Ramanujan described it as "the on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Divisor
In mathematics, a divisor of an integer n, also called a factor of n, is an integer m that may be multiplied by some integer to produce n. In this case, one also says that n is a multiple of m. An integer n is divisible or evenly divisible by another integer m if m is a divisor of n; this implies dividing n by m leaves no remainder. Definition An integer is divisible by a nonzero integer if there exists an integer such that n=km. This is written as :m\mid n. Other ways of saying the same thing are that divides , is a divisor of , is a factor of , and is a multiple of . If does not divide , then the notation is m\not\mid n. Usually, is required to be nonzero, but is allowed to be zero. With this convention, m \mid 0 for every nonzero integer . Some definitions omit the requirement that m be nonzero. General Divisors can be negative as well as positive, although sometimes the term is restricted to positive divisors. For example, there are six divisors of 4; they ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetraphobia
Tetraphobia () is the practice of avoiding instances of the digit . It is a superstition most common in East Asian nations. __TOC__ Rationale The Chinese word for "four" (, pinyin: sì, jyutping: sei3), sounds quite similar to the word for "death" (, pinyin: sǐ, jyutping: sei2), in many varieties of Chinese. Similarly, the Sino-Japanese, Sino-Korean and Sino-Vietnamese words for "four", shi (し, Japanese) and sa (사, Korean), sound similar or identical to "death" in each language (see Korean numerals, Japanese numerals, Vietnamese numerals). Tetraphobia is known to occur in Korea and Japan since the two words sound identical, but not at all in Vietnam because they carry different tones (in the case of the word for "four", whether it is the Sino-Vietnamese reading ''tứ'' or the more common non-Sino-Vietnamese reading ''tư'', neither sounds like the word for "death" which is ''tử'') and Vietnamese does not use Sino-Vietnamese numerals as often in the first place. Sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
