Everybody is aware of the worth of pi is 3.14…er, one thing, however how many individuals know the place the ratio got here from?

Actually, the ratio got here from nature—it’s the ratio between the circumference of a circle and its diameter, and it was at all times there, simply ready to be found. But who found it? In honor of Pi Day, right here’s a semi-brief historical past of how pi got here to be generally known as 3.14(1592653589793238462643383279502884197169…and so forth).

Editor’s be aware: This article initially printed in 2010. We’re rerunning it right this moment in honor of Pi Day, 3/14.

The historical past lesson

It’s arduous to pinpoint who, precisely, first grew to become acutely aware of the fixed ratio between the circumference of a circle and its diameter, although human civilizations appear to have been conscious of it as early as 2550 BC.

The Great Pyramid at Giza, which was constructed between 2550 and 2500 BC, has a fringe of 1760 cubits and a top of 280 cubits, which provides it a ratio of 1760/280, or roughly 2 times pi. (One cubit is about 18 inches, although it was measured by an individual’s forearm size and thus assorted from one particular person to a different.) Egyptologists consider these proportions had been chosen for symbolic causes, however, after all, we will by no means be too positive.

The earliest textual proof of pi dates again to 1900 BC; each the Babylonians and the Egyptians had a tough concept of the worth. The Babylonians estimated pi to be about 25/8 (3.125), whereas the Egyptians estimated it to be about 256/81 (roughly 3.16).Archimedes didn’t calculate the precise worth of pi, however reasonably got here up with a really shut approximation—he used 96-sided polygons to give you a worth that fell between 3.1408 and 3.14285.The Ancient Greek mathematician Archimedes of Syracuse (287-212 BC) is basically thought-about to be the primary to calculate an accurate estimation of the value of pi. He achieved this by discovering the areas of two polygons: the polygon that was inscribed inside a circle, and the polygon during which a circle was circumscribed (see determine above, proper).

Chinese mathematician Zhu Chongzhi (AD 429-500) used an identical methodology to approximate the worth of pi, utilizing a 12,288-sided polygon. His finest approximation was 355/113.

The approximate ratio for pi also appears in the Bible in 1 Kings 7:23:

“And he made a molten sea, ten cubits from the one brim to the other: it was round all about, and his height was five cubits: and a line of thirty cubits did compass it round about.”

(I ought to level out that the Biblical ratio for pi could possibly be extra correct than one may suppose, since cubits modified relying on an individual’s forearm size. So, assuming the Bible isn’t quoting cubits from the identical particular person every time…)

In the fifteenth century, Indian mathematician Madhavan of Sangamagramam found what’s now generally known as the Madhava-Leibniz series (named after German mathematician Gottfried Leibniz, who rediscovered the sequence within the seventeenth century), an infinite sequence that converges to 4. Madhavan subsequently calculated pi to 11 decimal locations.

Later, in 1707, Welsh mathematician William Jones was the primary to make use of the Greek letter pi (π) to indicate the fixed ratio, although it wasn’t till 1737 that Swiss mathematician and physicist Leonhard Euler popularized using the image. The π image was taken from the Greek phrase for “perimeter.”

The most correct calculation of pi earlier than the arrival of the pc was by D. F. Ferguson, who calculated pi to 620 digits in 1945 (beforehand, William Shanks had calculated pi to 707 digits in 1874, however solely 527 of mentioned digits had been appropriate).

Of course, then computer systems entered the image and calculating pi knew no bounds—starting with D. F. Ferguson’s calculation of pi to 710 digits in 1947 with a desk calculator to Takahashi Kanada’s calculation of pi to 206,158,430,000 digits in 1999 with a Hitachi SR8000.

Shigeru Kondo carried out the longest calculation of pi so far on October 19, 2011. Kondo used Alexander Yee’s y-cruncher program to calculate pi to 10 trillion digits, which is a document calculation for each supercomputers and residential computer systems.

So there you will have it—Egyptians calculated pi utilizing pyramids (or did they calculate pyramids utilizing pi?), Archimedes busted out the 96-gon, Zhu Chongzhi one-upped him with a 12,288-gon (or is that 12,192-upped him?), Ferguson calculated 620 digits by hand, and Kondo used a supercomputer to nab the present world document of 10 trillion digits.

Pi in popular culture

But wait—the obsession with pi isn’t simply restricted to mathematicians and scientists. Pi has a particular place in well-liked tradition, because of its prevalence in mathematical formulae and its mysterious nature. Even utterly non-cerebral exhibits, books, and films can’t assist however point out the favored fixed.

For instance, pi will get talked about in a scene from Twilight, during which vampire-boy Robert Pattinson recites the sq. root of pi (and on-the-ball Kristin Stewart shortly shuts him down).

The Simpsons can also be fairly into pi (and math references on the whole). In one scene, two younger ladies at a college for the gifted play patty-cake and say “Cross my heart and hope to die, here’s the digits that make pi, 3. 1415926535897932384…” In one other scene, an indication on the Springfield graveyard says “Come for the funeral, stay for the π.”

Yep, whether or not you prefer it or not, pi is in every single place. Here are just a few extra locations it’s popped up:

• The essential character within the award-winning novel (and 2012 movie) Life of Pi nicknames himself after the fixed.
• A round room within the Palais de la Découverte science museum in Paris is known as the pi room. The room has 707 digits of pi inscribed on its wall (although there’s an error starting on the 528th digit, because of William Shanks’ misguided calculations).
• In an episode of Star Trek: The Original Series, Spock instructions an evil laptop to compute pi to the final digit—which it can not do, after all, as a result of, as Spock explains, “the value of pi is a transcendental figure without resolution.”
• Givenchy’s PI cologne for men is marketed as a scent that “embodies the confidence of genius.”
• Both MIT and the Georgia Institute of Technology have cheers that embody “3.14159.”
• Several different films reference pi, together with the 1966 Alfred Hitchcock movie Torn Curtain, the 1995 Sandra Bullock thriller The Net, 1998 indie thriller Pi.

Finally, pi is maybe most rampant in popular culture on March 14—Pi Day! On Pi Day, nerds, geeks, and mildly geometry college students alike come collectively and put on pi-themed clothing, learn pi-themed books, and watch pi-themed movies, all whereas tinkering with our Raspberry Pi PCs.

Correction, March 14, 2013: An earlier model of this story mistakenly acknowledged that Archimedes’ estimate for pi was 3.1485. His precise estimate calculated pi to be between 3.1408 and three.14285. (If you common these two figures, you get an in-between level of three.141851.) We remorse the error.

Article initially printed March 13, 2010; up to date March 13, 2013 and March 14, 2023.