Five

Five (5) is the natural number following four and preceding six.

Table of contents

1 Five in mathematics
2 Five in numbering systems
3 Five in various cultures
4 Five is also

4.1 Other common uses

5 Five in music
6 Other usages
7 See also

Five in mathematics

Five is the third smallest prime number, the next is seven. Because it can be written as 2^(2^1)+1, five is classified as a Fermat prime.
The number 5 is a Fibonacci number, being 2 plus 3. The next Fibonacci number is 8.
Five is a factor of 10, so fractions with 5 in the denominator do not yield infinite decimal expansions, unlike most other primes. When written in the decimal system, all multiples of 5 will end in either 5 or 0.
While polynomial equations of degree 4 and below can be solved with radicals, equations of degree 5 and higher cannot generally be so solved. This is the Abel-Ruffini theorem. This is related to the fact that the symmetric group S_n is a solvable group for n ≤ 4 and not solvable for n ≥ 5.
While all graphs with 4 or fewer vertices are planar, there exists a graph with 5 vertices which is not planar: K₅, the complete graph with 5 vertices.
Five is also the number of Platonic solids.

In binary code five is 101
In ternary code five is 12
In quaternary numeral system code five is 11
In quinary five is 10; in senary code and all codes above (such as octal, decimal and hexadecimal) five is 5.
The Roman numeral for five is V, which comes from a representation of an outstretched hand.
In Greek alphabet, ε (epsilon) has numerical value of 5.
In Cyrillic alphabet, Е has numerical value of 5.
In Glagolitic alphabet, (dobro) has numerical value of 5.

There are five basic "pillars" of Islam.
Islamic people pray to Allah five times a day (Mohammed was said to have bargained it down with Allah from fifty).
According to the Maya mythology, we are now living in the Fifth World.
In the Oriental tradition, there are five elements (water, fire, earth, wood and metal). The Japanese names for the days of the week Tuesday through Saturday come from these elements, rather than from the planets.
In Cantonese, five sounds like the word "not" (symbol 唔). So when five appears in front of a lucky number, e.g. 58, the result is considered unlucky.

The number of cents in a nickel.
The number of appendages on a starfish.
The number of players on a basketball team.
The number of permanent members with veto power on the UN Security Council.
The number necessary to make a majority decision in the U.S. Supreme Court.
The five senses are sight, smell, hearing, touch and taste.
The five basic tastes are sweet, salty, sour, bitter and umame.
It takes five musicians to make a quintet, such as the Jackson Five.
Five babies born at one time are quintuplets. The most famous set of quintuplets were the Dionne Quintuplets born in the 1930s. *The word "quintessential" came from that elusive fifth element that completes the basic four elements (water, fire, air and earth).
Five is also the number of dots in a quincunx.
The number of points in a pentagram.
There are five sides in a pentagon.
Pentameter is verse with five repeating feet per line; iambic pentameter was the most popular form in Shakespeare.
Almost all amphibians, reptiles, birds and mammals which have fingers or toes have five of them on each extremity.
The Garden of Cyrus is a Pythagorean Discourse based upon the number 5.

The word "punch" comes from the Hindustani for five. Being true to the designation of punch, the drink Five Alive is named for its five ingredients.
Something that tries to bring an operation down or screw with the system can be called a "fifth wheel".
Aside from Hawaiian punch, the 50th state of the United states gives us the quinary TV show title Hawaii Five-O.
The Olympics have five interlocked rings as their symbol, representing the number of inhabited continents represented by the Olympians (counting North America and South America as one continent).

The name of the band The Fifth Dimension implies that they are transcending beyond even the fourth dimension (time) into a new inner dimension.
There is a British boy band called 5ive.
Other bands with "five" in their name include We Five and the Five Stairsteps.
The Vogues song "Five-o'clock World" came in reference to the hours 9 to 5 (ending at 5 p.m.), which are the hours of a standard work day. There are also five working days (non-week-ends) in a week.