1. Welcome to the Wonderful World of Pi!

2. So What is Pi?
Pi is a name given to the ratio of the circumference of a circle to the diameter. That means, for any circle, you can divide the circumference (the distance around the circle) by the diameter and always get exactly the same number. It doesn't matter how big or small the circle is, Pi remains the same. Pi is often written using the symbol π, and is pronounced "pie" just like the dessert.

3. A Wee Bit O’History of Pi
Ancient civilizations knew that there was a fixed ratio of circumference to diameter that was approximately equal to three.
The Greeks refined the process and Archimedes is credited with the first theoretical calculation of Pi.
In 1761 Lambert proved that Pi was irrational, that is, that it can't be written as a ratio of integer numbers.
Remember how I told you Archimedes died while drawing circles in the sand? Well here’s proof!

5. How many digits are there? Does it ever end?
Because Pi is known to be an irrational number it means that the digits never end or repeat in any known way.
But calculating the digits of Pi has proven to be a fascination for mathematicians throughout history. Some spent their lives calculating the digits of Pi, but until computers, less than 1,000 digits had been calculated.

6. The Most Digits Calculated….
In 1949, a computer calculated 2,000 digits and the race was on.
Millions of digits have been calculated, with the record held (as of September 1999) by a supercomputer at the University of Tokyo that calculated 206,158,430,000 digits.

7. The Most Digits Calculated….
Between April 19, 1998, and Feb. 9, 1999, 126 computers from eighteen different countries set a new record for calculating specific bits of using a program written by C. Percival. The calculation took a total of about CPU-hours and was done using idle CPU cycles under Windows 95 and Windows NT. The answer, starting at the th bit of is , so the 40 trillionth bit of is 0.
In December 2002, computer scientists Kanada, Ushio and Kuroda computed to a world record (more than one trillion) decimal digits, besting their previous world record of digits, set in The computation consumed more than 600 hours of time of a Hitachi SR8000 supercomputer (Peterson 2002, Kanada 2003).

8. Some Pretty Amazing Performances…
Memorizing Pi
Some Pretty Amazing Performances…
** Sim Pohann of Malaysia recited the first 67,053 digits of Pi with just 15 errors on 14 April It took him 15 hours and 15 minutes.
** Dr. Yip Swe Chooi, also of Malaysia, Grandmaster of Memory, recited the first 60,000 digits of Pi with just 44 errors on 25 July It took him 14 hours. ** Dave Turner recited the first 1,250 digits of Pi both forwards and backwards on 05 July 2005.
** Mats Bergsten of Sweden recited 9,778 digits of Pi on 21 March 2005 while juggling three balls!.

9. How many digits have been memorized?
Back in 2004 a high school sophomore by the name of Ryan Ly was able to successfully memorize and recite the first 800 digits of pi (in under 5 minutes!)
Not bad…
However…the current world record holder is Chao Lu of China who memorized 67,890 digits as of November 20, 2005.

10. An interview with Chao Lu
(These are some responses of his after setting the new world record)
1. How long did it take you to recite the 67,890 places ? It took me 24 hours 4 seconds to recite to the 67,890th place of Pi Did you take any breaks ? No. According to the rule set by GWR, the time between two numbers should be no more than 15 seconds. So there was no lunch time, no toilet break during my recitation How long did it take you to memorize the digits ? About one year.

11. 4. Are the 67,890 places as far as you got or did you even know more at some time ? I've got 100,000 digits of pi, and I was going to recite 91,300 digits of them. But I made a mistake at the 67,891th digit. It was "0" but I said "5" in my recitation Did you make any errors during your recitation ? If yes, how many ? I made a mistake at the 67,891th digit. That is the only one.

12. Let the competition begin!
Now it’s your turn!
Let the competition begin!