How many digits of Pi do you know?

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The LuigiManiac
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How many digits of Pi do you know?

Postby The LuigiManiac » Tue May 01, 2007 9:33 pm UTC

I was waiting to see if anyone else was going to kick off discussions here, but the lack of topics means that I will have to kick things off with a subpar idea. How many digits of Pi do you know off by heart?

Personally, I don't know very many (read: the first three digits) off by heart. I'm not the greatest at memorizing things.

EDIT:Apparently, someone posted another topic while I was getting this one made.
Spoiler:
THE CAKE IS A 3.141592653589...!

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Postby EvanED » Tue May 01, 2007 9:38 pm UTC

3.
14159 26535
89793 23846
26433 83279
50288 41971
69399 37510
58

Let's see... that's 53 digits, including the 3.

I used to know 72, because that's how many there were on a poster in my geometry class.

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Postby culled » Tue May 01, 2007 9:41 pm UTC

3.141592653
So ten, I don't think that's bad. It's not as good as Evan's but it's more than most people know and probably more then I'll ever need to use.

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Postby PaulT » Tue May 01, 2007 9:44 pm UTC

I only know what I know from that mnemonic, "how I need a drink, alcoholic of course, after the heavy lectures regarding quantum mechanics". So that's 13 if I've remembered it correctly.

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Postby gmalivuk » Tue May 01, 2007 9:46 pm UTC

3.14159265358979323846265338327950288419716939937510...

So, I guess, 50. I used to know quite a bit more, because I would change my university password to include the next ten digits every time I'd sufficiently memorized the 10 I was on.

But I suppose 50 isn't bad, since if I had to use it to compute the circumference of a circle as big as the galaxy, an exact knowledge of the radius would give me a figure off by only about 10^-29 meters.
Last edited by gmalivuk on Tue May 01, 2007 9:50 pm UTC, edited 1 time in total.
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Postby Torn Apart By Dingos » Tue May 01, 2007 9:47 pm UTC

3.14159265358

12 digits. I've known more, maybe three times that, which I memorized in a day, but those 12 have stuck.

I'm not so good at memorizing digit sequences. I don't use any tricks, such as pairing numbers (remembering "twelve" instead of "one, two"), I just say the digits in sequence quickly in my head. When I was younger, I thought such tricks would be cheating, and now I can't get out of the habit.
Last edited by Torn Apart By Dingos on Tue May 01, 2007 9:48 pm UTC, edited 1 time in total.

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Postby cmacis » Tue May 01, 2007 9:47 pm UTC

Off the top of my head:
Pi pi mathematical pi
3.14159265358979323846264338327
and the rest is fuzzy
952088

That's about as many as the windows scientific calc. I may stop at 42 digits.
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Postby warriorness » Tue May 01, 2007 9:50 pm UTC

I've stopped at 42 digits myself.

3. 1415 926 535 8979 323 8462 643 383 279 502 884 197169 or something like that. I broke up the groups in the way I memorized it (up to "8979" was on a poster in my elementary school math room).
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Postby bbctol » Tue May 01, 2007 9:55 pm UTC

By heart:
3.14159265358979323846

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Postby mister k » Tue May 01, 2007 10:58 pm UTC

2... I rather think you sully pi when you attempt to write it out numerically. Keep it in symbolic form and it is exact, and nice things happen when you take sine and cosine of it, rather than getting 0.00000000001.....

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Postby cmacis » Tue May 01, 2007 11:01 pm UTC

li ci pi pa vo pa mu so re

Other languages FTW.
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Postby dan » Tue May 01, 2007 11:05 pm UTC

gmalivuk wrote: I would change my university password to include the next ten digits every time I'd sufficiently memorized the 10 I was on.
I remember reading an anecdote about Richard Feynman, and how he would try breaking into scientists' lockers with pi or e as the combination, with a pretty good success rate.

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Postby cmacis » Tue May 01, 2007 11:08 pm UTC

I now know what I'm typing for the postgrad's code for their own computer lab. It makes beeps when buttons are pressed, so I know there's 5 digits. :)

Yes, I was the kid who managed to get admin access at school. :)
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Pi-like script

Postby GreatPokerHands » Tue May 01, 2007 11:38 pm UTC

All this talk of PI reminds me of a program I once saw that I thought would make a great animated signature.

It was a clever hack. The program had the first 50 or so digits of PI stored, and slowly churned them out, merrily scrolling away, then, when it got to the end, it simply generated random digits and continued scrolling along giving the impression it was dynamically calculating the digits. A total con!

How many people know >50 digits of PI (present posters excluded), especially when they were scrolling by a couple a second. I wonder how many people it fooled?

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Postby cmacis » Tue May 01, 2007 11:40 pm UTC

I know people who can go that far. I think it's something that needs the run up though. If it is on a time delay then not many people would realise after so long.
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Postby Akira » Tue May 01, 2007 11:54 pm UTC

Wow. I totally feel lame now for only knowing "3.14159"...
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Postby Xial » Wed May 02, 2007 12:02 am UTC

I learned about the first 30 by listening to the pi music video.

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Postby SpitValve » Wed May 02, 2007 1:16 am UTC

I can't do better than 3.14.

But I know a 12 year old girl who has it memorised up to about 90 paces or so...

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Postby grim4593 » Wed May 02, 2007 4:30 am UTC

3.1415926535898

That ain't bad. I can do the alphabet backwards too!
zyxwvutsrqponmlkjihgfedcba

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Postby Phi » Wed May 02, 2007 5:36 am UTC

3.14159265358979 is all I got to before my teacher would tell me to start paying attention.

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Postby Gordon » Wed May 02, 2007 5:39 am UTC

5986764341518487643135168489461316516848479646164986
461643434346464643434616431313134613461361313486468748641641684616163443463434641918997673689499779794169494613

Since Pi is irrantional and never repeats; since eventually the string of numbers I present is unrepeating, they will in fact eventually be a part of Pi and thus are a part of Pi.

If you wanted us to knowingly submit digits of Pi which we recognized to be a known part of Pi you should have specified as such.

Edit: I am hammered. Discuss.

Acutally don't because that doesn't belong in this forum.
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Postby EvanED » Wed May 02, 2007 5:48 am UTC

Gordon wrote:5986764341518487643135168489461316516848479646164986
461643434346464643434616431313134613461361313486468748641641684616163443463434641918997673689499779794169494613

Since Pi is irrantional and never repeats; since eventually the string of numbers I present is unrepeating, they will in fact eventually be a part of Pi and thus are a part of Pi.


This is not true.

For instance, the decimal 0.110100100010000100001000001.... is not repeating and hence irrational, but obviously doesn't even contain the substring '7'.

I do not know if pi has the property that any string of digits will appear, but it's far from certain.

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Re: Pi-like script

Postby warriorness » Wed May 02, 2007 6:18 am UTC

GreatPokerHands wrote:All this talk of PI reminds me of a program I once saw that I thought would make a great animated signature.

It was a clever hack. The program had the first 50 or so digits of PI stored, and slowly churned them out, merrily scrolling away, then, when it got to the end, it simply generated random digits and continued scrolling along giving the impression it was dynamically calculating the digits. A total con!

How many people know >50 digits of PI (present posters excluded), especially when they were scrolling by a couple a second. I wonder how many people it fooled?


There exist algorithms that calculate pi's digits extremely rapidly, much faster than linear time (which would be the minimum required for such an image). Why not just use those to calculate actual digits?

Hmm. Because that would require extremely accurate floating-point computation and a hell of a lot of RAM to store the digits. I'll post this anyway; it's an interesting thought.
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Postby poizan42 » Wed May 02, 2007 6:43 am UTC

I know ALL the digits of pi: 10 in base pi :wink:

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Postby Dingbats » Wed May 02, 2007 7:25 am UTC

3.1415926535897932384626433

25 decminals, 26 digits. I could recite those in sleep.

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Postby skeptical scientist » Wed May 02, 2007 7:29 am UTC

Is base pi actually useful for anything?
I'm looking forward to the day when the SNES emulator on my computer works by emulating the elementary particles in an actual, physical box with Nintendo stamped on the side.

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Postby EvanED » Wed May 02, 2007 7:40 am UTC

skeptical scientist wrote:Is base pi actually useful for anything?


It's really good for getting an exact representation of pi. ;-)

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Postby skeptical scientist » Wed May 02, 2007 7:57 am UTC

Yeah, but since that's not useful for anything, neither is base pi.
I'm looking forward to the day when the SNES emulator on my computer works by emulating the elementary particles in an actual, physical box with Nintendo stamped on the side.

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Postby evilbeanfiend » Wed May 02, 2007 8:42 am UTC

i know all the digits of pi.

0,1,2,3,4,5,6,7,8 and 9

i just don't know what order to put them in (or with what frequency they occur)
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Postby Patashu » Wed May 02, 2007 10:59 am UTC

3.1415926535897932384626433832795028841971

Which seems to be 40 decimal places.

I'm waiting on someone to memorize e or phi, though. Any takers?

EDIT: Oh, 69 is the next two decimal places. Now that's easy to remember. :)

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Postby cmacis » Wed May 02, 2007 12:34 pm UTC

We have an e page, and phi can be expressed exactly as 1/2(1+sqrt(5)). Off the top of my head: 1.61.
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Postby MFHodge » Wed May 02, 2007 1:54 pm UTC

3.141592653589

Although I sometimes get it wrong and say 3.14159265389, skipping the "5" in decimal #10. Not sure why, but it really doesn't come up that often.

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Postby Gelsamel » Wed May 02, 2007 2:13 pm UTC

3

I must enter a message when posting... apparently 3 doesn't count.
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Postby You, sir, name? » Wed May 02, 2007 2:43 pm UTC

3141592653 -- that's all I've learned so for.

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Postby gmalivuk » Wed May 02, 2007 3:43 pm UTC

Dingbats wrote:3.1415926535897932384626433

25 decminals, 26 digits. I could recite those in sleep.


Again (like with people who remember 2.71 for e), why do you stop at a point where the next digit is 8, and therefore your truncation has a much larger rounding error than necessary.

Edit: Remembering 1.61 as an approximation for 1.618 is similarly problematic.

Why can't people seem to remember 8s?
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Postby rhino » Wed May 02, 2007 4:05 pm UTC

pi: 3.1415926535897
phi: 1.61803398
e: 2.71828182


















...actually I just deliberately truncated all of those 1 digit before my memory allows, purely to annoy gmalivuk :)

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Postby Dingbats » Wed May 02, 2007 6:10 pm UTC

gmalivuk wrote:
Dingbats wrote:3.1415926535897932384626433

25 decminals, 26 digits. I could recite those in sleep.


Again (like with people who remember 2.71 for e), why do you stop at a point where the next digit is 8, and therefore your truncation has a much larger rounding error than necessary.


I didn't know the next digit was 8, naturally. :) Now I know, thanks. 3.14159265358979323846264338. Damn, stopping there feels unnatural, I need four more digits to make it 30.

EDIT: 3.141592653589793238462643383279 it is.

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Postby ++$- » Wed May 02, 2007 10:29 pm UTC

I know 53 -- which is EXACTLY the same number as the first person to respond to this thread. I was spooked by this and had to join the forums as a result.

I group them like this:
3. - 141 - 59 - 26 - 5358 - 979 - 323 - 84 - 626 - 43383 - 2795 - 0288 - 419716 - 93993 - 7510 - 58
It makes them easier to remember.

Phi: 1.618033989 = 10 digits (but the last is really an 8, rounded up)
e: 2.718281828459045 = 16 digits

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Postby EvanED » Wed May 02, 2007 10:39 pm UTC

++$_ wrote:I know 53 -- which is EXACTLY the same number as the first person to respond to this thread. I was spooked by this and had to join the forums as a result.
[snip]
e: 2.718281828459045 = 16 digits


Same there. Look at the e thread...

(You've got me by a longshot on phi though. I just know 1.618. I can give you the exact speed of light in meters per second though. ;-))

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Postby Oort » Thu May 03, 2007 1:59 am UTC

3.141592653589793238462643383279501884171693933

Or so.


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