3.1415926535897932384626433 That is as far as I can memorize. 25 digits. A fact about pi:
The decimal representation of Ï truncated to 11 decimal places is good enough to estimate the circumference of any circle that fits inside the Earth with an error of less than one millimeter, and the decimal representation of Ï truncated to 39 decimal places is sufficient to estimate the circumference of any circle that fits in the observable universe with precision comparable to the radius of a hydrogen atom.
How I remember it? I read some fantasy book I don't remember. There was a Griffen who remembered the first 3 numbers by counting the letters of each word in a sentence. "Yes (3) I (1) know (4)". So I added a little to it and ended up with:
Yes I know I ***** Anastasia I'm ****ed aren't you?
Feel free to add to it. Or try and get around the swears ._.
You can calculate pi by taking a Taylor sequence for the arctangent, which ends up equalling:
arctan (x) = X - X^3 / 3 + X^5 / 5 - X^ 7 / 7 ...
arctan 1 = pi / 4
So 4 * ( 1 - 1/3 + 1/5 - 1/7 ... ) = pi.
There are many ways to solve pi. Look on the [url=http://en.wikipedia.org/wiki/Pi]Pi article on Wikipedia for many other ways to solve for digits of pi.
