5 (number)
5 (five) is the
natural number following
4 and preceding
6.
The
SI prefix for 1000
5 is
peta (P), and for its reciprocal
femto (f).
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Evolution5glyph.png |
The evolution of our modern glyph for five cannot be neatly traced back to the Brahmin Indians quite the same way it can for 1 to 4. Later on the Kushana and Gupta Indians had among themselves several different glyphs which bear no resemblance to the modern glyph. The Nagari and Punjabi took these glyphs and all came up with glyphs that look like a lowercase "h" mirrored and turned upside down. The Ghubar Arabs transformed the glyph in several different ways, coming up with glyphs that look more like 4s or 3s than 5s. It was from those characters that the Europeans finally came up with the modern 5, though from purely graphical evidence, it would be much easier to conclude that our modern 5 came from the Khmer.
Five is the third smallest
prime number, after
2 and
3, and before
7. Because it can be written as 2^(2^1)+1, five is classified as a
Fermat prime. 5 is the third
Mersenne prime exponent. Five is the second
Wilson prime.
Five is the only prime number to end in the digit 5, because all other numbers written with a 5 in the ones-place under the decimal system are multiples of five. As a consequence of this, 5 is in base 10 a 1-
automorphic number.
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.
The number 5 is a
Fibonacci number, being
2 plus
3. The next Fibonacci number is
8. 5 is also a
Pell number.
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 Sn 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.
A
polygon with five sides is a
pentagon.
Figurate numbers representing pentagons (including five) are called
pentagonal numbers. Five is also a
square pyramidal number.
Five is the answer to the question asked at the very end of the mathematics quiz show in the movie
Little Man Tate. (Our young protagonist blurts out the answer, but the host mishears it as being the answer from the contestant to whom the question is posed, and declares him the winner.)
In numbering systems
*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 the
Greek alphabet, ε (
epsilon) has numerical value of 5.
*In the
Hebrew alphabet, ה (heh) has numerical value of 5.
*In the
Cyrillic alphabet,
Е has numerical value of 5.
*In the
Glagolitic alphabet,
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GlagolitsaDobro.gif |
(dobro) has numerical value of 5.
*The
kanji and
Chinese character for five are both 五, and its formal writing in Chinese is 伍 (
pinyin wǔ).
*The number of appendages on most
starfish, which exhibit
pentamerism.
*Almost all
amphibians,
reptiles,
birds and
mammals which have
fingers or
toes have five of them on each extremity.
* The maximum category on the
Saffir-Simpson Hurricane Scale, the most damaging.
* The
atomic number of
boron.
*
Messier object M5, a magnitude 7.0
globular cluster in the constellation
Serpens.
* The
New General Catalogue object NGC 5, a
magnitude 13
spiral galaxy in the
constellation Andromeda* The
Saros number of the
solar eclipse series which began on
April 4,
2720 BC and ended on
May 24,
1422 BC. The duration of Saros series 5 was 1298.1 years, and it contained 73 solar eclipses.
* The Saros
number of the
lunar eclipse series which began on
-2581 October 8 and ended on
-1084 March 24. The duration of Saros series 5 was 1496.5 years, and it contained 84 lunar eclipses.
*There are five basic "
pillars" of
Islam.
*
Muslims pray to
Allah five times a day (
Muhammad 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 norse mythology.
*In
Cantonese, five sounds like the word "not" (symbol 唔). So when five appears in front of a lucky number, e.g. 5
8, the result is considered unlucky.
*Using the Latin root, five musicians are called a quintet. One such group whose name celebrates their fiveness are the
Jackson Five. (In an episode of
Will & Grace guest-starring
Janet Jackson, she declared that 5 is a mystical number and for that reason she must have precisely 5 backup dancers).
*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 was a British
boy band called
5ive.
*Other bands with "five" in their name include
We Five and the
Five Stairsteps.
*The
Dave Clark Five and the
Ben Folds Five both named themselves after their lead singers, with an implied four others.
*
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.
*
5 is an album by
Lenny Kravitz.
*"Take Five" is a famous
jazz standard composed by
Paul Desmond. It counts five beats per bar.
Five is:
*The expression
five by five originates from the U.S. Military and refers to the five levels of signal strength and signal clarity in a radio transmission. The fifth, and highest level for each being, "Loud" and "Clear" respectively. Thus "five by five" was adapted to define anything ideal.
*The number of
oceans in the world.
*The number of cents in a
nickel. The U.S. nickel bears a portrait of
Thomas Jefferson. The Canadian nickel has a
beaver on its reverse.
*The denomination of the
U.S. dollar with
Abraham Lincoln's portrait.
*The designation of an
Interstate Highway that runs from
San Diego, California to
Blaine, Washington.
*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 umami.
*Five babies born at one time are
quintuplets. The most famous set of quintuplets were the
Dionne Quintuplets born in the 1930s.
*In
Astrology,
Leo is the 5th
astrological sign of the
Zodiac.
*The word "quintessential" came from that elusive fifth element that completes the basic four elements (water, fire, air and earth). There is also a movie called
Fifth Element.
*Part of the title of the
1970 movie
Five Easy Pieces, starring
Jack Nicholson and
Sally Struthers.
*The number of dots in a
quincunx.
*The number of points in a
pentagram.
*
Pentameter is verse with five repeating feet per line;
iambic pentameter was the most popular form in
Shakespeare.
*The expression "five-finger discount" refers to
shoplifting.
*The
five stages of grief are said to be shock, denial, anger, bargaining and acceptance.
*
The Garden of Cyrus 1658 by Sir
Thomas Browne is a Pythagorean Discourse based upon the number 5.
*
Giving five refers to slapping hands with someone as a sign of approbation.
*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).
*In
chess, the number of first titled
grandmasters.
*In
chess, the fewest number of moves a
pawn makes to a queening square.
*The number of
kyu (pupil) grades in
judo*
Five Tiger Generals*
Five-spice powder*
Five Principles of Peaceful Coexistence*
Five Dynasties and Ten Kingdoms Period*
Five the UK TV channel.
* In
rugby union, the number of the
lock forward who usually jumps at number 4 in the line-out.
* In
baseball, five represents the
third baseman's position.
* In the
DOS Shell and
Windows, the F5 key refreshes a directory listing or folder window. In
Internet Explorer, the F5 key refreshes the current webpage.
* The
Pentium, coined by
Intel Corporation, is a fifth-generation
x86 architecture
microprocessor.
*
5, a character in the comic strip
Peanuts* Historical years:
5 A.D.,
5 B.C., or
1905*
Enid Blyton's
The Famous Five* The automobile
Renault 5* The
juice brand
5 Alive* To 'hang five' in
surfing is to surf with one foot partly off the board.
* Five was the designation of the main robot character from the movie
Short Circuitnah:Macuilli
