3

3
Basic Information
Cardinal Number	three
Ordinal Number	third
Roman Numeral	III
Greek Numeral	Γ´
Factorization	3
Different Representations
Binary Form	112
Ternary Form	103
Quaternary Form	34
Quinary Form	35
Senary Form	36
Septenary Form	37
Octal Form	38
Nonary Form	39
Undecimal Form	311
Duodecimal Form	312
Tridecimal Form	313
Quattuordecimal Form	314
Quindecimal Form	315
Hexadecimal Form	316
Septendecimal Form	317
Octodecimal Form	318
Novemdecimal Form	319
Vigesimal Form	320
Unvigesimal Form	321
Duovigesimal Form	322
Trevigesimal Form	323
Quattuorvigesimal Form	324
Quinvigesimal Form	325
Hexavigesimal Form	326
Septenvigesimal Form	327
Octovigesimal Form	328
Novemvigesimal Form	329
Trigesimal Form	330
Untrigesimal Form	331
Duotrigesimal Form	332
Tretrigesimal Form	333
Quattuortrigesimal Form	334
Quintrigesimal Form	335
Hexatrigesimal Form	336
Previous	2
Current	3
Next	5

3 is the second prime number and the second single digit prime number. 3's prime factors are 1 and 3. It's the first odd prime, because the only even prime number is 2.

It is also the first Fermat prime, the first pi-prime number, the first prime of the form floor, and the first Mersenne Prime.

Proofs

• — 3 can be divided by 1.

• — 3 cannot be divided by 2.

• — 3 can be divided by 3.

• Therefore, it has 2 factors.

As an Exponent of Mersenne Number

$2^3-1$, which is the number 7, is a prime number. It is the 2nd Mersenne Prime.

Relationship with other numbers

The numbers before

• 2 is the first prime number. It is the only even prime number.
• 1, the number before 2, is not a prime number.

The numbers after

• The next number, 4, is the first composite number, and a square number. It is the square of 2.
• The next odd number, 5, is a prime number.
  • There are no odd numbers between 3 and 5, and they are two numbers apart. As a result, they are twin primes.
• 7, the odd number following 5, is a prime number.
  • 3 and 7 are four numbers apart, therefore, they are cousin primes.
• 9, the odd number following 7, is not a prime number. It is a square number and the first odd composite number.

Usage

General

• Trilogy refers to a set of three works of art that are connected, either as a single work or three individual works.

Science

• Lithium's atomic number and the number of electrons are 3.
• Tritium (hydrogen-3) has a nucleon number of 3.

Sports

• In basketball, a shot behind the three-point arc is worth three points, unless in the 3x3 variant.
• In baseball, 3 strikes are required for the player to be considered "out", and 3 outs are required for the attacking team to exchange with the opposing team.

Video Games

• In The Legend of Zelda series, there is a sacred relic called Triforce, which consists of three separate golden triangles.

et:3

Trivia

• There are only three consecutive odd numbers. 3, 5, 7. Later it's impossible because every 3rd odd number is composite, because it's divided by 3.
• 3 is the only additive prime whose digits add up to 3. It is because all the other numbers whose digits add up to a number that is divisible by 3 is divisible by 3.

Prime Numbers 1-1,000