# “Guess what?! I got a fever, and the only prescription is more pi!”

As we reported a year or so ago, there is a small industry of people interested in computing the digits of $\pi$.  Back then they computed the first 5 trillion digits of $\pi$ and destroyed the old record of 2.7 trillion digits.

It was announced on slashdot recently that a person in Japan has extended the computation to 10 trillion digits!  The website is here.  At the moment there isn’t many details, but this person has been involved in the $\pi$ calculation community for awhile, so there is every reason to expect that this is legit.

Of course, as pointed out by one of the slashdot commentators, if you take the first 50 digits of $\pi$:

$\pi \approx 3.14159265358979323846264338327950$

then that is already enough so that if you compute the circumference of the known universe using just these 50 digits, then your error is less than the width of a human hair!

That said, the associated improvements in algorithms, computation, etc. may be useful in other settings.  Plus, it’s just darn cool.

# Happy Pi Day!

Pi Day!

As you might know, March 13th is $\pi$ Day.  If you’re obsessive about these things, the $\pi$ Second is March 14 at 1:59:26 p.m.   Today is a great day to eat a piece of pie (of course, every day is a great day to eat pie!).  Or, even better, you could tackle the pie themed Problem of the Month!

If you’re interested in $\pi$ Day related stuff, you can also check out the Pie Day website which has T-shirts, the $\pi$ Clock, and other cool stuff.

Some Fun Facts about $\pi$:

1. There is the famous Indiana Pi Bill which was proposed in 1897 and among other things supposedly gave a way to square the circle despite the fact that mathematicians had proven it was impossible to square the circle in 1882.  It also proposed that $\pi = 3.2.$
2. Everybody knows that the series $\sum_{n>0} \frac{1}{n^2}$ converges, but in fact it Euler showed in 1735 that it converges to $\pi ^{2}/6$!
3. Most people also know that $\pi$ is irrational, some know it is transcendental, but nobody knows about the distribution of the digits 0,1,2, 3, 4, 5, 6, 7, 8, 9 in $\pi$.  That is, experimental evidence suggests that each digit appears 1/10 of the time, but nobody knows how to prove it!  In fact nobody even knows if all the digits occur infinitely often!
4. $\Pi$ has been calculated to a trillion digits and the Guinness-recognized record for remembered digits of π is 67,890 digits, held by Lu Chao, a 24-year-old graduate student from China.  But if you’d like to compute the circumference of any circle that fits in the observable universe to a precision comparable to the size of a hydrogen atom, then a mere 39 decimal places is sufficient!
5. It’s not just a math constant, $\pi$ appears in nature.  For example in Einstein’s Field Equations.

If you have some spare room in your brain, you can certainly fill it with the digits of $\pi$.  The secret, apparently, is the art of Piphilology:  memorizing a poem/story/etc. where each word has the number of letters equal to the next digit of $\pi$.  For example,

How I need a drink, alcoholic of course, after the heavy lectures involving quantum mechanics.

Or, if you’re hardcore you can spend spring break memorizing the Cadaeic Cadenza!

Failure is just success rounded down.