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<span style="font-family: 'Cambria">{{Divisibility|Divisibility of 2|2}}</span>;
 
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Revision as of 00:24, 7 September 2015

Divisibility of 2Divisibility of 2:
All even numbers are divisible by 2, which are
numbers with 0, 2, 4, 6, or 8 as the last digit.
Example: 2,624 is divisible by 2. Its last digit is 4.
;


2 is the first prime number in the base ten numbering system. It is said to be the only even prime number, as all other even numbers are divisible by 2, making them composite.

2 is also the only prime number without an "e" in its name. This is because 2 is the only even prime number, and all odd numbers have an e in their names.

Proofs

  • Yes — 2 can be divided by 1.
  • Yes — 2 can be divided by 2.
  • Therefore it only has two factors.

The number 2 is the only even prime number because every even number is divisible by 2. Therefore, an even number can only have 2 factors if it is 2 because they can't be prime if they are divisible by an integer other than 1 and themselves.

Unique Properties

  • A number is considered even if it is divisible by 2.
  • 2+2=2*2=22
  • 1/1+1/4+1/9+1/16+...+limit of 1/K2 (as k approaches infinity)=2
  • -e-e=2, according to Euler's identity.

Relationship with other numbers

The numbers before

  • There are no prime numbers before 2. 
  • 1, the number before 2, is not a prime number, because it only has 1 factor; itself.

The numbers after

  • The next odd number, 3, is a prime number.
  • 4 is the first composite number.
  • 5, the odd number following 3, is a prime number.

Usage

Science

  • The number of polynucleotide strands in DNA double helix.
  • The atomic number of helium. Also the number of protons, neutrons, and electrons in a helium atom.
  • The number of electrons in the first full shell of an atom.
  • Group two elements consists of alkaline earth metals and have a valence of two.
  • Period two elements consists of elements of lithium to neon and are classified as such since they have two electron shells.
  • Deuterium / hydrogen-2, an isotope of hydrogen, has a nucleon number of two.

Technology

  • The resin identification code used in recycling to identify high-density polyethylene.

Sports

  • In basketball, any shot not outside the three-point field goal is equal to two points, unless the player who threw the ball is fouled while attempting the shot.
  • In Association football, the scoring of two goals by one individual in a single match is referred to as a brace.