This article discusses the number three. For the year AD 3, see 3. For other uses of 3, see 3 (disambiguation) tre-/ter- (from Latin)

Cardinal	3 three
Ordinal	3rd third
Numeral system	ternary
Factorization	prime
Divisors	1, 3
Roman numeral	III
Unicode representation of Roman numeral	Ⅲ, ⅲ
prefixes	tri- (from Greek)
Binary	11
Octal	3
Duodecimal	3
Hexadecimal	3
Hebrew	ג (Gimel)
Arabic	٣

3 (three) is a number, numeral, and glyph. It is the natural number following 2 and preceding 4.

In mathematics

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• Three is the first odd prime number, and the second smallest prime after two.
• Three is the first Fermat prime (2^2º + 1).
• Three is the first Mersenne prime (2² - 1).
• Three is the second Sophie Germain prime.
• Three is the second Mersenne prime exponent.
• Three is the first lucky prime.
• Three is the first Genocchi prime.
• Three is the second factorial prime (2! + 1).
• Three is the first unique prime due to the properties of its reciprocal.
• Three is the second triangular number.
• Three is the only prime which is one less than a perfect square. Any other number which is one less than a perfect square will be the product of the numbers one more than, and one less than, the square root of said square.
• Three non-collinear points determine a plane and a circle.
• Three is the fourth Fibonacci number and the third that is unique. It is also the second Lucas prime and the second Stern prime.
• Three is the fourth open meandric number.
• Vulgar fractions with 3 in the denominator have a single digit repeating sequences in their decimal expansions, (.000..., .333..., .666..., .999...)
• 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. Because of this, the reverse of any number that is divisible by three (or indeed, any permutation of its digits) is also divisible by three. For instance, 1368 and its reverse 8631 are both divisible by three (and so are 1386, 3168, 3186, 3618, etc..). See also Divisibility rule.
• A triangle is the most durable shape possible, the only "perfect" figure which if all endpoints have hinges will never change its shape unless the sides themselves are bent.
• 3 is the only integer between e and π.

More on [ 3 (number) ]

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Three car-thieves arrested: LAHORE ANTI Vehicles Lifting Staff, Iqbal Town division, claimed to have busted Tanzil-u... http://cli.gs/p5r5s
Lahore (Lahore) Tue, 15 Dec 2009 00:25:28 -0000
Three car-thieves arrested: LAHORE ANTI Vehicles Lifting Staff, Iqbal Town division, claimed to have busted Tanzil-u... http://cli.gs/p5r5s
Only 2 points separate the bottom three NHL Atlantic Division. Let's go Flyersssssssssss!!!
seattlemaverick (Chas Salcedo) Mon, 14 Dec 2009 22:28:25 -0000
Only 2 points separate the bottom three NHL Atlantic Division. Let's go Flyersssssssssss!!!
Wiltshire FXL - Monday - Mens - Division Three: Real Falkirk beat F.F.C (1 - 14) http://is.gd/4TGXT
FutsalSwindon (@Futsal Swindon) Mon, 14 Dec 2009 22:12:54 -0000
Wiltshire FXL - Monday - Mens - Division Three: Real Falkirk beat F.F.C (1 - 14) http://is.gd/4TGXT
Wiltshire FXL - Monday - Mens - Division Three: Black Horse beat The Cyclones (9 - 7) http://is.gd/4TGXT
FutsalSwindon (@Futsal Swindon) Mon, 14 Dec 2009 22:12:53 -0000
Wiltshire FXL - Monday - Mens - Division Three: Black Horse beat The Cyclones (9 - 7) http://is.gd/4TGXT
Wiltshire FXL - Monday - Mens - Division Three: Slideaway beat BMI Bullets (5 - 11) http://is.gd/4TGXT
FutsalSwindon (@Futsal Swindon) Mon, 14 Dec 2009 20:25:27 -0000
Wiltshire FXL - Monday - Mens - Division Three: Slideaway beat BMI Bullets (5 - 11) http://is.gd/4TGXT
Wiltshire FXL - Monday - Mens - Division Three: Zurich beat Misshit United (12 - 3) http://is.gd/4TGXT
FutsalSwindon (@Futsal Swindon) Mon, 14 Dec 2009 20:02:59 -0000
Wiltshire FXL - Monday - Mens - Division Three: Zurich beat Misshit United (12 - 3) http://is.gd/4TGXT

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