Today is Pi day for all you geeks out there... I have a question about Pi?

Question

When I was in school pi = 22/7 or 4 units (circumference)/ 1.27 units (the diameter). But when you divide 22/7 or 4/1.27, you get 3.1428571428571428571 and 3.149606299212598, respectively. So my question is how is the "real" Pi number, 3.1415926535897932384626..., derived?

Thanks everyone for your answers... They were all so good that I will have the public decide the best answer.

Answer 1

22/7 is of course an approximation. I think you can get the real number using a MacLauren or Taylor expansion - if you want more accuracy, you just take the expansion to more terms. You never ever run out of opportunity to add more terms, hence all these mad people who calculate pi to a squillion zillion decimal places

Answer 2

The real pi is derived from infinite series of numbers which allow you to work out pi to any degree of accuracy desired
for example pi^2/6 = 1/1 + 1/2^2 + 1/3^3 + 1/4^2 +1/5^2 + ......


but there are other series which relate pi to a sum of an infinite number of terms

Answer 3

Pi is the ratio of the circumference of a circle to its diameter: 3.14159 continuing as an infinite series.

On a more interesting note: A REAL-LIFE "Rain Man" spoke yesterday (15 Mar 2004) of his exhaustion after counting his way into the record books by reciting the number Pi to more than 22,500 decimal places.

Daniel Tammet, 25, took just over five hours to perform the feat, sitting in front of a blackboard once used by Albert Einstein before an audience at Oxford University’s Museum of the History of Science.

Mr Tammet, from Herne Bay, Kent, is recognised as one of a select band of so-called "savants" - people capable of extraordinary mental feats linked to medical conditions.

Unlike the central character in the film Rain Man, starring Dustin Hoffman as the autistic savant Raymond, Mr Tammet developed his extraordinary ability to "see" numbers after childhood epileptic seizures.

While he has outgrown his early disability, multilingual Mr Tammet remained able to perform unusual feats of memory and has founded a company teaching people skills for learning maths and languages.

See link below for the whole story.

Answer 4

Pi can be calculated by an infinite series. I don't remember what it was. When you were at school pi did not equal 22/7, that was just an approximation.

http://www-groups.dcs.st-and.ac.uk/~history/HistTopics/Pi_through_the_ages.html

Answer 5

the same system i.e. ratio of circumference / diameter of the circle, but more precisely that 22/7

Answer 6

The value "22/7" is an approxmate value which is easy
to remember. The actual value is:

3.141592653589793238462643383279502884197169399375105820974944592..............................

Visit these sites for more information:

http://en.wikipedia.org/wiki/Pi
http://mathforum.org/dr.math/faq/faq.pi.html
http://www.angio.net/pi/piquery
http://www.joyofpi.com/pi.html
http://www-groups.dcs.st-and.ac.uk/~history/HistTopics/Pi_through_the_ages.html
http://mathworld.wolfram.com/Pi.html
http://mathforum.org/dr.math/tocs/pi.middle.html
http://www.php.net/pi

Answer 7

It has something to do with a calculation involving a circle - which as you know, is infinite (contains infinite angles).

Answer 8

http://en.wikipedia.org/wiki/Pi

See "Calculating π"