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## Nicholas Sze of Yahoo Finds Two-Quadrillionth Digit of Pi299

gregg writes "A researcher has calculated the 2,000,000,000,000,000th digit of pi — and a few digits either side of it. Nicholas Sze, of technology firm Yahoo, determined that the digit — when expressed in binary — is 0."
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## Nicholas Sze of Yahoo Finds Two-Quadrillionth Digit of Pi

• #### Re:So, what is the digit in decimal? (Score:3, Informative)

by Anonymous Coward on Thursday September 16, 2010 @06:50PM (#33605494)

We only know how to calculate it in binary (or any base that is a power of 2). You can't convert to decimal without know all the rest of the digits.

• #### Re:You fail math forever (Score:2, Informative)

on Thursday September 16, 2010 @06:56PM (#33605540)
What they should have said is: The two quadrillionth digit in the binary expansion of pi is 0.
• #### Re:You fail math forever (Score:3, Informative)

on Thursday September 16, 2010 @07:04PM (#33605634) Homepage Journal
100-4
101-5
110-6
111-7
• #### Re:So, what is the digit in decimal? (Score:5, Informative)

on Thursday September 16, 2010 @07:09PM (#33605692)

We only know how to calculate it in binary (or any base that is a power of 2). You can't convert to decimal without know all the rest of the digits.

Parent is correct, digits of pi can be calculated independently in base 2, 4, 8, 16 or 2^n since the 1990s [maa.org]. So, it is possible to calculate the 2,000,000,000,000,000th number of pi without calculating the digits before that one. Now, if we want to calculate the digit in decimal (or converse the binary digit to decimal), we need to calculate all of the two-quadrillion digits. Knowing this digit is in itself not very interesting.

<fairwater@g[ ]l.com ['mai' in gap]> on Thursday September 16, 2010 @07:13PM (#33605718) Homepage

The interesting thing about this article is how they calculated the digits. They broke the problem up into small pieces and had them calculated in parallel. This approach isn't something that's new or all the unique, but what is is applied to is. Most mathematical calculations are done in a near linear fashion, not in parallel. So for them to be able to do this is a big step forward in how we approach these types of problem in the future.

At least with regards to calculating Pi, it's isn't particularly new. They first used this parallel method back in the 1980's.

• #### Re:how do they do it (Score:3, Informative)

on Thursday September 16, 2010 @07:20PM (#33605772) Homepage Journal

Regardless of what actually happened, there isn't any computation that requires keeping data in memory rather than hard disk. Memory is just faster, if you need more space for the computation, you can always actually use the 100 disks.

• #### Re:Oh yeah? (Score:1, Informative)

by Anonymous Coward on Thursday September 16, 2010 @07:22PM (#33605778)

You're wrong, because TFA is discussing the binary representation of pi. It's either a 1 or a 0.

• #### Re:Last Digit? (Score:4, Informative)

on Thursday September 16, 2010 @08:58PM (#33606442)

Pi is NOT irrational! It is transcendental. Look it up!

http://en.wikipedia.org/wiki/Transcendental_number [wikipedia.org] :

All real transcendental numbers are irrational, since all rational numbers are algebraic.

• #### Re:an so are an infinite other digits in that numb (Score:4, Informative)

on Friday September 17, 2010 @02:06AM (#33607916) Journal

The hexadecimal digit extraction formula for PI (that allows you to skip calculating the previous hex digits) is already known. It can calulcuate the N'th hexadecimaldigit of Pi without calculating most of the previous digits: http://en.wikipedia.org/wiki/Bailey%E2%80%93Borwein%E2%80%93Plouffe_formula [wikipedia.org]

A slower generalized version that can extract the n'th digit of Pi in any base (including decimal) has also been found: http://web.archive.org/web/19990116223856/www.lacim.uqam.ca/plouffe/Simon/articlepi.html [archive.org]

• #### Re:an so are an infinite other digits in that numb (Score:3, Informative)

<calum@callingthetune.co.uk> on Friday September 17, 2010 @03:46AM (#33608338) Homepage
The thing that I find funny, is that had they used the Bailey-Borwein-Plouffe formula, [wikipedia.org] they could have saved themselves some very considerable computing resources.

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