this post was submitted on 19 May 2025
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[–] [email protected] 96 points 1 month ago (2 children)

This beats the approximations used in ancient Sumer (3.1065) and China (3). Try contacting their respective records bodies.

[–] [email protected] 40 points 1 month ago* (last edited 1 month ago) (3 children)

Gotta say, using 3 just feels like giving up due to laziness, even in 1200BC.

Also it's interesting how the Chinese entries basically stop between 1400 and 1949, whereas European names are far more present during this era. Some Japanese ones, too. I wonder how comprehensive this page is.

[–] [email protected] 39 points 1 month ago (4 children)

Rounding pi to 3 is just the engineering way. It's close enough to get the job done and then I don't have to worry about decimal places. However, using pi=3 typically undershoots your calculations, so personally I like to use pi=4

[–] [email protected] 22 points 1 month ago (3 children)

An error margin of less than 5% (even better, biased in a known direction) is more than good enough for plenty of use cases.

An error margin of more than 25% on the other hand, is seldom acceptable.

[–] [email protected] 20 points 1 month ago

Nah, it's fine. Trust me I use pi=4 in every calculation I do that uses pi and I haven't ever run into any issues at all

(I'm not that type of engineer, I never do anything with pi)

[–] [email protected] 7 points 1 month ago

It's called safety factor

[–] [email protected] 3 points 1 month ago

One is an error margin, the other a factor of safety!

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[–] [email protected] 9 points 1 month ago

Sometimes zero decimals is enough precision even in 2025…

…but also because of laziness…

[–] [email protected] 7 points 1 month ago* (last edited 1 month ago)

AFAIK the Chinese knew that the value between that of the encompassing shape that meets the circle at tangeants to the inscribed shape whose edges meet the same equidistant points gives us the approximation of pi. So did archimedes, and maybe even the babylonians.

So while a triangle yields about 3 and satisfies the theorem, you could also theoretically draw a 96 gon and 192 gon like Liu Hui for an accuracy of 9x10^5.

Personally I just memorize 22/7 or use the Leibniz infinite series if I have to.

[–] [email protected] 20 points 1 month ago (3 children)

Doesn't have the famous

ln(640320³ + 744)/√163

for some reason. Accurate to 14 decimal places I believe which is more accurate than what you need for 99.9% of its applications.

[–] [email protected] 27 points 1 month ago (1 children)

So to avoid memorizing a 15-digit number you'll memorize a 13-digit equation?

[–] [email protected] 6 points 1 month ago* (last edited 1 month ago)

More like you memorize that to show off. There are tons of high schoolers that know pi to dozens of digits, it’s not really exciting. But most high schoolers fundamentally don’t understand logs.

[–] [email protected] 11 points 1 month ago (3 children)

It's been said that with 15 decimals, you can calculate the circumference on the observable universe with a precision of the width of an atom.

[–] [email protected] 9 points 1 month ago* (last edited 1 month ago)

Not quite, according to JPL https://www.jpl.nasa.gov/edu/news/how-many-decimals-of-pi-do-we-really-need/

15 decimal places, for Voyager 1 - We have a circle more than 94 billion miles (more than 150 billion kilometers) around, and our calculation of that distance would be off by no more than the width of your little finger.

[–] [email protected] 5 points 1 month ago

This is an exaggeration.

The universe's radius is around 46.5 billion light years (around 4.4 * 10^26 meters), the error introduced of using 15 decimals of pi is around the order of 10^-16. Thus the error of calculating the circumference would be in the order of

8.8*10^26 * 10^-16 = 8.8*10^10 meters
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[–] [email protected] 45 points 1 month ago (3 children)

During lockdown I had a bit of time on my hands so I memorised all the digits of pi in the right order.

[–] [email protected] 30 points 1 month ago (3 children)

I memorized them in numerical order. First there's a bunch of 0s then a bunch of 1s, followed by 2s, and so on.

[–] [email protected] 12 points 1 month ago (3 children)

Yeah but how many 0s do you have before you get to the first 1? I've been working on it but still don't have a definite answer.

[–] [email protected] 8 points 1 month ago (1 children)
[–] [email protected] 5 points 1 month ago (1 children)

Is that actually true or is that an unsolved problem?

[–] [email protected] 6 points 1 month ago* (last edited 1 month ago)

It's believed to be true to a high degree.

Pi is infinite. It's also believed with a high degree of certainty (but not proven) to be a normal number, which basically means all the digits are evenly distributed over the infinite series. So if that is true, there would be an infinite number of 0s. Theoretically it could suddenly turn out to not be normal after a certain amount of digits are found, and then 0 could just stop entirely after a certain point, but this is incredibly unlikely.

[–] [email protected] 6 points 1 month ago

I don't know the exact number but it's quite a few of them

[–] [email protected] 3 points 1 month ago

At least 4 or 5

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[–] [email protected] 25 points 1 month ago (2 children)
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[–] [email protected] 5 points 1 month ago (1 children)

Hey, me too! I also did e and the Feigenbaum constant, though.

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[–] [email protected] 26 points 1 month ago (4 children)

If anyone is curious, I looked it up and The Guinness Book of World Records currently recognizes Rajveer Meena as the world record holder for Pi memorization. He recited 70'000 digits of Pi while blindfolded in about ten hours in 2015. I can't even begin to understand how someone could actually do that.

[–] [email protected] 10 points 1 month ago

I memorized 100 digits some years ago using physical memory. I would type the digits of pi on the numpad and memorize the movements of my hand, how it feels and which button goes when by position. Then when I would have to recite it, I'd imagine a numpad, move my hand and just say the number that corresponds to the imaginary button I'm pressing.

Don't know if that could work for 70k digits though

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[–] [email protected] 25 points 1 month ago (2 children)

3.1 I hold the world record for memorizing the shortest length of pi decimals.

[–] [email protected] 22 points 1 month ago (2 children)
[–] [email protected] 11 points 1 month ago

This guy engineers

[–] [email protected] 6 points 1 month ago
[–] [email protected] 7 points 1 month ago* (last edited 1 month ago) (3 children)

I have memorized fewer digits: " "

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[–] [email protected] 19 points 1 month ago (2 children)
[–] [email protected] 16 points 1 month ago (1 children)
[–] [email protected] 4 points 1 month ago
[–] [email protected] 7 points 1 month ago (2 children)

Three, no more, no less. Three is the number of pi. Four should not be pi, neither two. Five is right out.

[–] [email protected] 3 points 1 month ago

1, 2, 5!

3 sir!

Oh yes! 3!

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[–] [email protected] 13 points 1 month ago (1 children)

3.11

You could say he was all mixed up, and he didn’t know what (else) to do.

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[–] [email protected] 13 points 1 month ago (1 children)

Does anyone else really want to write them now just to get an official rejection letter?

[–] [email protected] 19 points 1 month ago

If I write them enough and get enough rejection letters, can I then get accepted as the Guinness World Records record holder for most rejections of Guinness World Record records?

[–] [email protected] 11 points 1 month ago (1 children)

Is there a Guiness world record for classes or categories of individuals with the most rejection letters from the Guiness World Records association?

[–] [email protected] 4 points 1 month ago

If you pay for it I'm sure they would gladly add it

[–] [email protected] 8 points 1 month ago

Every 5y/o is better at copying the Guinness World Records logo.

[–] [email protected] 8 points 1 month ago

Pi for workgroups.

[–] [email protected] 7 points 1 month ago

This isn't really a meme

[–] [email protected] 6 points 1 month ago

Well, shit.

This guy beat me to it.

[–] [email protected] 4 points 1 month ago

I like how the filename is "NoFair.webp". Hiding a funny little message in the filename is classy.

[–] [email protected] 4 points 1 month ago

Now I want to see the original letter. For some reason this reminds me of David Thorne (27bslash6)

https://27bslash6.com/bob.html

[–] [email protected] 3 points 1 month ago

I hold 2 GWR for the Reddit Secret Santa.

Anyone that participated during a couple years qualified.

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