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The mathematical constant PI is what you get if you divide the circumference of a circle by the diameter. It's always the same fixed number regardless of the size of the circle. Fact is, for any circle, it's always three and a bit times further round the outside than it is straight across the middle. The figure is quoted to various accuracies, like 3.14, or twenty-two divided by seven, or 3.142, 3.14159, or...


However, one of the curious things about the number is that it keeps on going, can it be infinitely?, raising some interesting mathematical and philosophical issues.

There are other numbers that are irrational and go on forever like this. For example, Root2 and Natural logarithm e

Here's PI to a greater accuracy...


1415926535 8979323846 2643383279 5028841971 6939937510
5820974944 5923078164 0628620899 8628034825 3421170679
8214808651 3282306647 0938446095 5058223172 5359408128
4811174502 8410270193 8521105559 6446229489 5493038196
4428810975 6659334461 2847564823 3786783165 2712019091
4564856692 3460348610 4543266482 1339360726 0249141273
7245870066 0631558817 4881520920 9628292540 9171536436
7892590360 0113305305 4882046652 1384146951 9415116094
3305727036 5759591953 0921861173 8193261179 3105118548
0744623799 6274956735 1885752724 8912279381 8301194912
9833673362 4406566430 8602139494 6395224737 1907021798
6094370277 0539217176 2931767523 8467481846 7669405132
0005681271 4526356082 7785771342 7577896091 7363717872
1468440901 2249534301 4654958537 1050792279 6892589235
4201995611 2129021960 8640344181 5981362977 4771309960
5187072113 4999999837 2978049951 0597317328 1609631859
5024459455 3469083026 4252230825 3344685035 2619311881
7101000313 7838752886 5875332083 8142061717 7669147303
5982534904 2875546873 1159562863 8823537875 9375195778
1857780532 1712268066 1300192787 6611195909 2164201989
...and so on.

If you'd like a downloadable version of this to a million decimal places, it's available FREE in the collection of FREE BOOKS on the site of Project Gutenberg under the title of PIMIL10.TXT

To a greater accuracy, there are mathematical algorithms for generating it. More about this later perhaps.

Also see Xyroth's PI page which has links to some other constants.

Incidentally, the value of PI isn't copyright anyone as it is has no creator, and is a mathematical fact regardless of any humans, God(s), or computers. It is free of the laws of the Universe as it is emergent from the concept of Euclidean space. Like it or not, there it is, mathematical chaos hiding in basic law at a fundamental level. In effect it's an emergent form of the mathematical relationships between things in a theoretical space which is independent of the physical universe. Same thing with root 2. It can't be different from what it is.

I hope you find pages such as this PI page at www.zyra.org.uk useful! If so... [response]

Update: Although PI is true, unchanging, and is what it is regardless, there's now a philosophical change of importance. PI should never have been PI (3.141 etc) in the first place. It should have been the True Circle Constant which is twice as big, or to put it another way, 2*PI, which is 6.283185, the ratio of the circle's circumference and radius. This has been termed Tau, and it makes more sense to use it in equations than to use PI. For more about this, see the Tau Manifesto at http://tauday.com/

Tau has many of the good things that PI has, for example it is an infinitely long decimal which people might like to remember to an uncanny number of places. In formulae, they tend to end up with 2*PI rather than PI. So, it would have made more sense if the constant had been better chosen originally. Tau Day was on the 28th of June 2010, because it was 6-28.

Upon meeting aliens, let's not be surprised if they are without 3.141 and instead use 6.283185.

Here's Tau to more places...