3 (number)
This article discusses the number three. For the year AD 3, see 3. For other uses of 3, see 3 (disambiguation)3 (
three) is a
number,
numeral, and
glyph. It is the
natural number following
2 and preceding
4.
Three is the first odd
prime number, and the second smallest prime after
two. It is both the first
Fermat prime (2
2º + 1) and the first
Mersenne prime (2
2 - 1), as well as the first
lucky prime. However, it's the second
Sophie Germain prime, the second Mersenne prime exponent, the second
factorial prime (2! + 1), the second
Lucas prime, the second
Stern prime.
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. In the Perrin sequence, however, 3 is both the zeroeth and third
Perrin numbers.
Three is the fourth
open meandric number.
[Vulgar fraction]]s 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
.
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Evolution3glyph.png |
Three is often the largest number written with as many lines as the number represents. The
Romans tired of writing 4 as IIII, but to this day 3 is written as three lines in Roman and
Chinese numerals. This was the way the
Brahmin Indians wrote it, and the
Gupta made the three lines more curved. The
Nagari started rotating the lines clockwise and ending each line with a slight downward stroke on the right. Eventually they made these strokes connect with the lines below, and evolved it to a character that looks very much like a modern 3 with an extra stroke at the bottom. It was the Western
Ghubar Arabs who finally eliminated the extra stroke and created our modern 3. (The "extra" stroke, however, was very important to the Eastern Arabs, and they made it much larger, while rotating the strokes above to lie along a horizontal axis, and to this day Eastern Arabs write a 3 that looks like a mirrored 7 with ridges on its top line):
٣In fonts with
text figures, 3 usually has a descender, for example,
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TextFigs036.png |
, though in some
French fonts it has an ascender instead of a descender.
Pointed version
A common variant of the digit 3 has a pointed top, similar to the character
ezh, sometimes used to prevent people from falsifying a 3 into an 8.
* White light is composed of the mixture of the three additive
primary hues: red, green, and blue.
*
Globular Cluster M3 (also known as Messier Object 3 or NGC 5272) is a globular cluster in the Canes Venatici constellation.
* The Roman numeral III stands for
giant in the
Yerkes spectral classification scheme.
* The Roman numeral III (usually) stands for the third-discovered satellite of a planet or minor planet (e.g.
Pluto III)
* Three is the
atomic number of
lithium.
* There are three generations of fundamental
leptons (
electron,
muon,
tauon and their
neutrinos) and three groups of flavours of
quarks (up-down, charmed-strange, top-bottom).
*The
Holy Trinity in
Christian doctrine (or
trinity in general), is God both as a single entity and as three entities: the Father, the Son and the Spirit. This is also known as
Tripartite division.
*The
Three Wise Men visited
Jesus after his birth
*A devout
Muslim tries to make a
pilgrimage to all three holy cities in
Islam:
Mecca,
Medina, and
Jerusalem*King
Solomon states in
Ecclesiastes 4:12: "A three-ply cord is not easily severed." Examples of this concept of
three-ness in
Judaism are:#The three
Patriarchs:
Abraham,
Isaac, and
Jacob#The
three pilgrim festivals (
Sheloshet HaRegalim):
Passover,
Shavuot, and
Sukkot#The three leaders of the Jewish nation during their 40 years of wandering in the desert:
Moses,
Aaron, and Miriam#The
Tanakh is comprised of 3 sections:
Torah,
Nevi'im, and
Ketuvim#There are 3 daily
prayer services:
Shacharit,
Mincha, and
Maariv#There are three divisions of Jews:
Kohen,
Levi, and
Israel#
Shimon Hatzaddik taught: "On three things the world stands: On
Torah, on prayer, and on acts of kindness" (
Pirkei Avoth 1:2). Rabban
Shimon ben Gamliel taught: "The world continues to exist because of three things: justice, truth, and peace" (ibid. 1:18)
*
Hamantaschen, a filled cookie served on
Purim, has 3 corners which represent the biblical
Haman's ears or his pockets
*The three
Doshas (weaknesses) and their
antidotes are the basis of
Ayurvedic medicine in
India.
*The three
Gunas underlie action, in the
Vedic system of knowledge. There is also the concept of
Trimurti in
Hindu tradition.
*The process of
synthesis in
Hegelian
dialectic creates three-ness from two-ness.
Three (三, formal writing: 叁,
pinyin san1) is considered a
good number in
Chinese culture because it sounds like the word "alive" ("
pinyin sheng1), compared to
four that sounds like the word "death".
Counting to three is common in situations where a group of people wish to perform an action in
synchrony:
Now, on the count of three, everybody pull! Assuming the counter is proceeding at a uniform rate, the first two counts are necessary to establish the rate, but then everyone can predict when "three" will come based on "one" and "two"; this is likely why three is used instead of some other number.
Some
computer users may use "3" as an alternate to the letter "
E", often in jest or to prevent search engines from reading their messages. This form of code is an example of basic
Leetspeak.
Luck, especially bad luck, is often said to "come in threes".
Some cultures in history have a place for people of
third gender.
*On
computer keyboards, the "3" key may be used to type the
pound sign.
*On most telephone keypads, the "3" key is also associated with the letters "
D", "
E", and "
F".
*In
ASCII, the code for "3" in hexadecimal is 33. This is the only character in ASCII such that a large file consisting of a single character has identical-looking hexadecimal and normal representation.
*The glyph "3" may be used as a subsitute for
yogh () when that character is not available.
*Three is the minimum odd number of voting components for simple easy
redundancy checks by direct comparison.
*Three is approximately
pi (actually closer to 3.14159) when doing rapid engineering wags or estimates. The same is true if one wants a rough-and-ready estimate of
e, which is actually approximately 2.7183.
*In
music, the Roman numeral iii is the
mediant scale degree,
chord, or
diatonic function, when distinguished III = major and iii = minor.
*Three is the number of performers in a
trio.
*The 3|4 time signature of Western classical music tradition (Three beats to a measure, with the quarter note comprising the beat.) is said to represent the Holy Trinity of Christian doctrine, Father, Son and Holy Spirit. It is for this reason that it is often utilized in compositions which were written for use in ecclesiastical rites, or that are inspired by scriptural/spiritual themes and texts.
*Three is important to popular American
rock group,
The White Stripes, and has become one of the trademarks of their style. Their third single was entitled
The Big Three Killed My Baby and in 2005 their lead singer has changed his name to
Three Quid.
*It is also is in the name of many music groups, including
Three Dog Night,
3 Doors Down,
Three Days Grace, and
3 Inches of Blood. The band
(3) uses the number alone as its moniker.
*Béla Bartók wrote three piano concertos. Camille Saint-Saëns wrote three completed, numbered symphonies.
*The third song on the album
Protection by
Massive Attack is called
Three. The lyrics refer continually to the perceived magical properties of the number.
*In
rugby union, 3 is the jersey number of the starting
tighthead prop. It is also the number of points received for a successful drop goal or penalty kick.
*In
baseball, 3 is the number of strikes before the batter is
out and the number of outs per side per inning. It also represents the
first baseman's position.
*In
basketball, a shot made from
behind the three-point arc.
*Also in basketball, 3 represents the
small forward position.
*Retired number of former baseball players
Babe Ruth,
Joe Medwick,
Bill Terry,
Harmon Killebrew, and
Dale Murphy.
*Is the number of the famous
NASCAR stock car that
Dale Earnhardt drove for nearly 20 years before his death in 2001. He won 6 out of his 7 championships while driving the #3 car. No one has driven the 3 car since his death.
*In
American football, 3rd down is the do or decide down. If insufficient yardage is gained to achieve a
first down, which starts a new series of downs, then coach/quarterback/coach in charge (CIC)/team is faced with fourth down: Shall we attempt immediate success and risk failure and giving other side good field position ... or punt to establish good defensive position while other side is on offensive?
*In both American and
Canadian football, the number of points received for a successful
field goal.
*In Canadian football, the last down before a team loses possession on downs. Usually, a team faced with a third down will punt (if far from the opponent's goal line) or attempt a field goal (if relatively close).
*An
Ironman triathlon consists of three events, a 2.4 mile (3.86 kilometer) swim, a 112 mile (180.2 kilometer) bike ride, and a 26.2 mile (42.2 kilometer) marathon run.
For other uses and related terms, see also 3 (disambiguation)Three is:
*
Three is a mobile phone operator.
*The number of stars in "Pacific's triple star" in the
God Defend New Zealand, one of
New Zealand's two national anthems.
*The
"third way" is a political term applied to a variety of "third choice" options that some offer as an alternative to dichotomous situations which may otherwise appear polarized.
*The phrase "Third time's the charm" (or, rarely, "Three time's the charm") usually means that the third time a person attempts something, he or she will succeed
*Three-bean salad is an appetizer containing three types of beans, such as
kidney,
yellow, and
green beans
*The
television VHF channel most often used for hooking up
VCRs and/or
video game systems. If it is otherwise occupied by a local broadcaster, then channel 4 is used instead.
*On most phones, the 3 key is associated with the letters
D,
E, and
F, but on the
BlackBerry it is the key for
U and
I.
*The designation of the
Crowsnest Highway in
Alberta and
British Columbia.
"In Memory of 3" - a phrase about
NASCAR driver
Dale Earnhardt, who drove the number 3 car. It can also refer to a
2004 ESPN television movie about Earnhardt's life called,
3: The Dale Earnhardt Story.
*
No. 3 -
1997 Korean
gangster comedy written and directed by
Neung-han Song**"the magic number", according to
De La Soul.
**"the magic number", according to
Multiplication Rock.
*In
Astrology,
Gemini is the 3rd
astrological sign of the
Zodiac.
*The number 3 is often used as a
literary device to provoke a feeling of unnaturalness, as
twos are much more common in nature (
limbs,
hemispheres,
eyes, etc). This is a prevailing
theme in
Ray Bradbury's novel
Fahrenheit 451. The aliens and their machines in the 2005 film
War of the Worlds were associated with features recurring in threes: eyes, legs, fingers, etc, for this same reason.
*Three
Rings of Power were wielded by the
Elves in
J. R. R. Tolkien's Middle-earth legendarium.
*In tarot, card No. 3 is "the Empress"
*3 is the number of novels or films in a
trilogy and the number of interconnected works of art in a
triptych3 A.D.,
3 B.C.,
1903,
2003, etc.
*
Tricyclopedic Book of Threes
