π is a mathematical constant that represents the ratio of a circle's circumference to its diameter. It is typically approximated to 3.14159. The document discusses the history and properties of π. It notes that Archimedes first approximated π around 250 BC and that the symbol π was established in mathematics by Euler in 1737. π is defined as an irrational and transcendental number with an infinite number of digits and no discernible pattern. March 14th is celebrated internationally as Pi Day in honor of the date written as 3/14 in the US date format.

1. The international mathematical constant :
 Athina

2. What is π?
 At Euclid’s geometry, the mathematical constant π is a real number.
 The name/the symbolization :
I. «π»
II. Pi
III. Archimedes’ constant
 It is defined :
I. As the ratio of a circle's circumference to its diameter,
II. Or as the ratio of a circle's area to the square’s area, which has a side
equal to the circle’s radius,
III. Or as the complete rotation that a circle does in order to roll up to a line.

3. Historical Information
 Back in 250 B.C., Archimedes, by using polygons, created an algorithm in his
attempt to approach π.
 About 150 A.D., Ptolemaist approximately estimated the number 3.1416 for
π.
 In 1706, mathematician William Jones was the first who used the symbol “π”.
Afterwards, it was actually established in mathematics bibliography by the
well known Swiss mathematician Leonhard Euler in 1737.

4. Properties
 π is an irrational number.
 π is a transcendental number too.
 Because of its transcendental nature the creation of a squared circle with
rule and compass, is impossible.
 Infinite number of digits.

5. Birthday
 The mathematical constant of pi is celebrated every year on 14 of March
(14/3 and according to Americans 3/14 ).
 Additionally in Europe, people celebrate π every 22/7 because 22 divided by
7 equals to 3,14 .
 This day is named «Pi day».

6. Random Facts
 Everything can be found at the digits of π,
 Einstein ‘s birthday is 14/3 (3/14/1879),
 We know the first 12,1 trillion digits of π,
 π is being studied since the Babylonian’s time, which
means that humanity puzzles over π for almost 4.000
years,
 The sequence of the π digits has no pattern.

7. The sound of …π!
 https://www.youtube.com/watch?annotation_id=anno
tation_3884270529&feature=iv&src_vid=OMq9he-
5HUU&v=wM-x3pUcdeo

8. SOURCES:
 http://ypervatikop.blogspot.gr/2010/12/blog-post_23.html
 https://el.wikipedia.org/wiki/%CE%A0_(%CE%BC%CE%
B1%CE%B8%CE%B7%CE%BC%CE%B1%CF%84%CE
%B9%CE%BA%CE%AE_%CF%83%CF%84%CE%B1%
CE%B8%CE%B5%CF%81%CE%AC)
 http://1lyk-dramas.dra.sch.gr/new/index.php/teyxos-no-
4/22-i-efimerida-mas/teyxos-4/46-i-pagkosmia-stathera-
p-3-14
 https://www.google.gr/search?q=%CF%80+3,14&safe=of
f&client=firefox-b-
ab&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjO1J6
_tNHSAhUHWxQKHdrlBQ0Q_AUICCgB&biw=1280&bih
=837

9. SOURCES:
 https://el.wikipedia.org/wiki/%CE%A4%CE%B5%CF
%84%CF%81%CE%B1%CE%B3%CF%89%CE%B
D%CE%B9%CF%83%CE%BC%CF%8C%CF%82_
%CF%84%CE%BF%CF%85_%CE%BA%CF%8D%
CE%BA%CE%BB%CE%BF%CF%85
 https://el.wikipedia.org/wiki/%CE%A0_(%CE%BC%
CE%B1%CE%B8%CE%B7%CE%BC%CE%B1%CF
%84%CE%B9%CE%BA%CE%AE_%CF%83%CF%
84%CE%B1%CE%B8%CE%B5%CF%81%CE%AC)

10. THE END