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by anguilla on June 1st, 2004
Pi is the ratio of the circumference of a circle to its diameter. To put it another way, it's the length of the circumference divided by the length of the diameter.
Pi always works out to be the same value, no matter what size the circle is. So Pi is a Big Deal because it lets you easily measure the length of the curved line that makes up a circle.
Pi = C/D, so if you know the diameter and Pi, you can calculate the circumference.
IF you do the math, and divide the circumference by the diameter, you'll get 3.14159265358979323846264338327950288419716939937510.....
-- where the dots represent the fact that no matter how long you keep dividing, it never comes out even and the pattern of numbers doesn't repeat. It has reportedly been calculated out to 206 billion digits!!
There are charts that describe the history of Pi, which goes back to the Babylonians (2000 BC), and how accurately (or inaccurately) Pi has been calculated through the years. I'm sorry I can't make it appear in neat columns here, but you can see it neatly if you go to http://www-gap.dcs.st-and.ac.uk/~history/HistTopics/Pi_chronology.html
Even though the rough value of Pi was known long before his time, the first theoretical calculation seems to have been carried out by Archimedes of Syracuse (287-212 BC).
---http://www-gap.dcs.st-and.ac.uk/~history/HistTopics/Pi_through_the_ages.html
I have altered the answer in response to comments from readers. Sorry for any mistakes.
by singwell-is off researching a lot on February 16th, 2007
Wikipedia: The mathematical constant π is an irrational real number, approximately equal to 3.14159, which is the ratio of a circle's circumference to its diameter in Euclidean geometry.
Pi is special because , no matter how many decimal places you take it to, it never repeats a number or a sequence of numbers.
The numerical value of π truncated to 500 decimal places is:
3.141592653589793238462643383279502884197169399375105820974944592307816406286
208998628034825342117067982148086513282306647093844609550582231725359408128481 117450284102701938521105559644622948954930381964428810975665933446128475648233 786783165271201909145648566923460348610454326648213393607260249141273724587006 606315588174881520920962829254091715364367892590360011330530548820466521384146 951941511609433057270365759591953092186117381932611793105118548074462379962749 56735188575272489122793818301194912
The value of π has been known in some form since antiquity. As early as the 19th century BC, Babylonian mathematicians were using π = 25⁄8, which is within 0.5% of the true value.
The Egyptian scribe Ahmes wrote the oldest known text to give an approximate value for π, citing a Middle Kingdom papyrus, corresponding to a value of 256 divided by 81 or 3.160.
It is sometimes claimed that the Bible states that π = 3, based on a passage in 1 Kings 7:23 giving measurements for a round basin as having a 10 cubit diameter and a 30 cubit circumference. Rabbi Nehemiah explained this by the diameter being measured from outside rim to outside rim while the circumference was the inner brim; but it may suffice that the measurements are given in round numbers.
Principle of Archimedes' method to approximate πArchimedes of Syracuse discovered, by considering the perimeters of 96-sided polygons inscribing a circle and inscribed by it, that π is between 223⁄71 and 22⁄7. The average of these two values is roughly 3.1419.
The Chinese mathematician Liu Hui computed π to 3.141014 in AD 263 and suggested that 3.14 was a good approximation
by Jack wears love COAT on January 2nd, 2008
Consider any circle of any radius.
The circumference of this circle always is little more than 3 times its diameter.
And this "little more" is always one-seventh of its diameter.
So the circumference is always 3+(1/7) of its diameter, which you can write as (21/7)+(1/7)=(22/7).
This value, 22/7 is called as "pi".
by Ivo on December 29th, 2008
But what is the Platonic marriage number, where the product of pi digits 3141592654 = 129,600?
by Isaac on April 16th, 2009
It doesn't have almost infinite digits. It was discovered that it has about 12 trillion decimal places, which is no where near infinity. :-)
by Roger Kovaciny on December 29th, 2008
It slays the natives if you can tell them that pi equals 3.1415926--which is easy to remember from the number of letters in the phrase "Yes, I want a drink; alcoholic of course."
by Steven_S3187 on April 26th, 2011
Anguilla's answer is excellent. In response to the second part of your question, every number has infinite (not almost) digits. For whole numbers, it's an infinite string of zeros: 1.000000... For other numbers it's other digits,which may repeat, converge, etc.
by xxtaytay4everxx on April 26th, 2011
This will make EVERYTHING clear, TRUST ME, just click here(you know you want to) ------------------->http://pi.ytmnd.com/
by kabug31 on April 26th, 2011
fith grade i learned it so burn!!!!!!!!!!!!!!!!!!!!!!
by Alicebee123 on March 12th, 2009
opps I learned that in 7th grade im sorry!
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Comments
Thorough answer.
by Andy Is Wicked Married to Penal Colony on June 13th, 2004
Actually, 22/7 is 3 1/7, which is 3.142857142857142857... Pi is a much more irrational number.
by DeuceOfSpades on June 29th, 2004
by Quirkie on September 16th, 2005
this is what I was searching for.
by Akshay Agarwal on March 7th, 2005
Very unhelpful reference to 22/7
by Les Toth on March 15th, 2005