This is topic What is 17% of 37? in forum Books, Films, Food and Culture at Hatrack River Forum.


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Posted by TL (Member # 8124) on :
 
I need to know what 17% of 37 is and I don't have a calculator handy.

Anyone?
 

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Posted by Tstorm (Member # 1871) on :
 
6.29
 

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Posted by TL (Member # 8124) on :
 
Thanks!
 

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Posted by King of Men (Member # 6684) on :
 
Hatrack - now also a desktop calculator!
 

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Posted by HollowEarth (Member # 2586) on :
 
http://services.valdosta.edu/javascript/calculate.html
 

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Posted by Dagonee (Member # 5818) on :
 
I'm going to need the 3,567,987th digit of pi, now.
 

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Posted by Dagonee (Member # 5818) on :
 
Apparently it's 6.

Ain't the Internet grand?
 

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Posted by ssywak (Member # 807) on :
 
Are you sure? Last time I checked, it was 5.

Hmmm...why would it have changed?
 

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Posted by Dan_raven (Member # 3383) on :
 
42
 

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Posted by CaySedai (Member # 6459) on :
 
my computers have all had calculators - Start, Program, Accessories, Calculator.

But for a fun one, go here. You can also download it for PC or Mac.
 

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Posted by Enigmatic (Member # 7785) on :
 
Dag, that link is completely awesome!

Oh wow, I am such a geek!
 

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Posted by Dagonee (Member # 5818) on :
 
You think that's bad - I'm tempted to download a couple hundred thousand digits and see if they're randomly distributed.

Not very tempted, but still. I actually thought about it.
 

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Posted by Dagonee (Member # 5818) on :
 
My member number is at position 8,806.

My birthday (year included) is at 19,955,891.

My wedding date (year included) is at 191,702,548.

My Hatrack registered date (year included) is at 54,471,205.
 

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Posted by King of Men (Member # 6684) on :
 
See, the thing about emacs is that it does this kind of thing for you! Who could resist a text editor that's also a calculator, and indeed psychologist, email reader, syntax highlighter, and Tetris game? Don't listen to the carping critics who say that emacs has everything but a kitchen sink; they're wrong, emacs does have a kitchen sink. And a battery of las-blasters to destroy all opposition! Death to vi!
 

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Posted by fugu13 (Member # 2859) on :
 
If only it had a decent text editor.


 

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Posted by Bob the Lawyer (Member # 3278) on :
 
It's just 37 x 0.17. Can't people do math without calculators any more?
 

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Posted by Bob_Scopatz (Member # 1227) on :
 
We should do a "pi-whack" It's like google whack, except you go to find a sequence that only appears ONCE in the whole of pi.

Rules:

The sequence must be less than 10 digits long (we'll just have to see if that works out...)
 

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Posted by Bob_Scopatz (Member # 1227) on :
 
Or..., what's the shortest sequence of digits that does NOT appear in pi?

I found a string of 9 zeros is NOT in the first 200 million digits of pi.

A string of 8 zeros is in there.

Weird.
 

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Posted by Dagonee (Member # 5818) on :
 
03301974 and 30031974 are not in the first 200 million digits of pi.
 

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Posted by Corwin (Member # 5705) on :
 
OK, weird-not-in-pi sequences aside, I have a thing to say about numbers: in Rouen we had a chemistry teacher who when he had to make multiplications between large numbers would take the log of those, add them up and then calculate 10 to the power of the result... in his head! o_O That's one weird feat, I tell you!
 

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Posted by Bob_Scopatz (Member # 1227) on :
 
In other words, you were taught by Rain Man.




(joking aside, that is amazingly cool.)
 

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Posted by Corwin (Member # 5705) on :
 
Too bad it was chemistry though...
 

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Posted by rivka (Member # 4859) on :
 

 

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Posted by Corwin (Member # 5705) on :
 
Well, don't get me wrong, I love chemistry... Especially physical chemistry... When it's more like physics... Oh well, I love physics, who am I trying to kid anyway?
 

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Posted by rivka (Member # 4859) on :
 

 

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Posted by Corwin (Member # 5705) on :
 
Btw, you people know that you can just google the answer, right?

Edit: rivka, you look a little green, is everything alright?
 

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Posted by Bob_Scopatz (Member # 1227) on :
 
I liked Bio-Chemistry best of all. I was hopeless at Physics and standard Chemistry. I did better in Organic Chemistry. But then I discovered the nexus between chemistry and behavior and finally started understanding it. I LOVED my upper-division class on the chemistry of hormones and neurotransmitters.

It also helped that the class sizes were smaller and the prof was able to take a closer interest in each student.

I like Newtonian physics. I can't wrap my mind around anything like Relativity or Quantum Mechanics. I'm too directly empirical.
 

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Posted by Corwin (Member # 5705) on :
 

quote:

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I can't wrap my mind around anything like Relativity or Quantum Mechanics.

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Uh, I've been to Physics contests for which I had to learn those, and while I was able to solve problems, I can't say I actually *understood* those theories... And my father, who's a Physics teacher, and quite a good one too, also had problems with Quantum theory throughout University. So you're in good company, Bob, if I'm allowed to say so...
 

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Posted by James Tiberius Kirk (Member # 2832) on :
 
There's always the mental math way:

code:

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= 17%(37)
= 10%(37) + 5%(37) + 2%(37) 
= 10%(37) + (10%(37)) / 2 + (1%(37)) * 2 
= 3.7 + (3.7 / 2) + (.37) * 2
= 3.7 + 1.85 + .74 
= 6.27

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It's easy once you get used to doing it this way.

--j_k

[ May 30, 2005, 04:48 PM: Message edited by: James Tiberius Kirk ]
 

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Posted by Corwin (Member # 5705) on :
 
0.37*2 being, of course, 0.74...
 

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Posted by Mike (Member # 55) on :
 

quote:

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Originally posted by fugu13:
If only it had a decent text editor.

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That's what viper-mode is for.

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But really, my favorite calculator is using vim to pipe text to bc.
 

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Posted by Corwin (Member # 5705) on :
 
Sometimes I wish I knew more bio-chemistry though... I'm reading "Darwin's Radio" by Greg Bear right now and parts of it read "blablablablabla" to me...
 

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Posted by Bob_Scopatz (Member # 1227) on :
 
That's Greg Bear's fault, not yours...
 

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Posted by Tatiana (Member # 6776) on :
 
The best way I know to get a feel for relativity and quantum mechanics is to play with them in real life. Everyone should build their own home accelerator, you know?

No but seriously, I read tons of descriptive books first, relativity for laymen, einstein explained, etc. My favorite for quantum mechanics is "QED (Quantum Electrodynamics) The Strange Theory of Light and Matter" by Richard P. Feynman. Then took the problem solving courses later. It helped a whole lot in understanding what we were actually doing when we solved the problems.

P.S. Another one of my very favorite science for laymen type books is The Character of Physical Law, also by RPF.

[ May 30, 2005, 01:50 PM: Message edited by: Tatiana ]
 

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Posted by Corwin (Member # 5705) on :
 

quote:

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Originally posted by Bob_Scopatz:
That's Greg Bear's fault, not yours...

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You're most probably right. I've read Gregory Benford's Timescape and Frank Herbert's White plague and didn't feel the need of a physics/chemistry book to better understand them. I guess Greg Bear just didn't know when to stop with the details...

And Tatiana, yeah, it's probably better to first read some descriptive books, but when those things are in your high-school Physics class you might not have the time for that... As for the contests, there were lots of other things to learn, so I kinda had to go to problem solving directly. I loved them, don't get me wrong - otherwise I wouldn't have cared enough to want to go to those contests, right? - but they are quite difficult theories to "feel"...
 

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Posted by James Tiberius Kirk (Member # 2832) on :
 

quote:

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Originally posted by Corwin:
0.37*2 being, of course, 0.74...

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*coughs*

--j_k
 

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Posted by Corwin (Member # 5705) on :
 
0.05 + 0.04 being, of course, 0.09...

Here, have some medicine for the cough! It sound awful!
 

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Posted by Bob_Scopatz (Member # 1227) on :
 
You know, there's an easy way to test the randomness of pi.

Every sequence of n digits should be equally probable. I propose taking a sample of sequences at various lengths and then plotting the distribution of the number of times each appears in the first 200 million digits of pi.

Basically, there shouldn't be wild fluctuations in frequency of the various n-length sequences. But...what fluctuation is there should obey some fairly straightforward rules of probability.

I suspect at the very least we would get a bell-shape on the frequency distribution centering on the mean frequency for sequences of length = n. I can't think of a good reason for it to follow any other distribution.

Can anyone else?
 

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Posted by fugu13 (Member # 2859) on :
 
There's no reason a transcendental number like pi needs to use the number 9, much less have a uniform distribution of it.
 

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Posted by Dagonee (Member # 5818) on :
 
I'd bet frequency of each digit would be roughly equal, but I'm not sure if that's enough to be random. Wouldn't the order count, too? 123456789009876543211122334455667788990000998877665544332211... will have roughly equal frequencies over the long term. I could make it even more so by moving the starting digits in a methodical fashion and rotating through. But it's not random, is it?

I am so far out of my depth here.
 

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Posted by Bob_Scopatz (Member # 1227) on :
 
fugu, I thought the question was whether or not pi's sequence of digits is random. Maybe Dag was the one who asked that.

Anyway, we used to have to test our "random number generators" in the early days of using personal computers to run experimental apparatus. To do that, we could check frequencies of digits or look at runs of particular digits.

Basically, the logic goes that a run of five zeroes in a row should be equally likely as the sequence 12345 or the sequence 43211 or any other sequence of five digits.

I see no reason to suspect that pi is composed of a random sequence of digits, to be honest. It is a number that expresses the stable relationship between the circumference and the diameter of a circle, no? So, it's based in a physical reality that is an inviolate law of geometry. Why would that have any randomness to it at all?

But the question has come up about whether the sequence that IS pi is indeed random or not.

I don't know, but I know how to test it.
 

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Posted by Bob_Scopatz (Member # 1227) on :
 
Dag, my suggestion is to work with sequences of length = 8 or higher, and then see if we can find their frequencies.

000000000
should show up roughly as many times as
000000001
000000002
999999999
123456789
414141414
and
293735822

It wouldn't take too many sequences to test this.

I suspect it's non-random. But I have no real sense of whether it will be or not.
 

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Posted by Dagonee (Member # 5818) on :
 
Ah, OK. I misread your procedure in the post above.
 

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Posted by fugu13 (Member # 2859) on :
 
You can just evaluate the sequence to see if its 95% likely pi is the result of a generator choosing among ten possibilities, using a sample size of whatever length you desire.
 

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Posted by Bob_Scopatz (Member # 1227) on :
 
fugu...

Can you fill that in for me? I come at this stuff from a brute-force empirical background, so I'm not sure I'm understanding your method or the statistical (probability) metric you'd use to guage 95% confidence limit...
 

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Posted by Corwin (Member # 5705) on :
 
[aside] You gotta love our ability to derail threads! I mean, here's a thread about 0.17*37 (?!?) and it goes through chemistry, learning Relativity and Quantum theories, hard SF books, and randomness of Pi! Way to go, Hatrack! [/aside]
 

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Posted by Bob_Scopatz (Member # 1227) on :
 
And now it's a thread about how awesome hatrack is.



We also have really cool Graemlins.
 

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Posted by fugu13 (Member # 2859) on :
 
All we'd have to do would be to come up with a random variable that reflects the various outcomes and had a normal distribution, then see if the distribution over a lengthy sequence from pi was in the 95% confidence interval for the rv.
 

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Posted by imogen (Member # 5485) on :
 

quote:

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The string 01062005 did not occur in the first 200000000 digits of pi after position 0.

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So Wednesday is a pi-less day!

Luckily today and tomorrow are ok.
 

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Posted by Dagonee (Member # 5818) on :
 
Isn't that fun, imogen? I have no idea why, but it's oddly satisfying.
 

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Posted by Minerva (Member # 2991) on :
 
Here are some ways to test the randomness of a number: http://www.cs.tufts.edu/g/250P/classpages/RandTests.html

That page was written for a bit stream (so you would use those exact techniques on the binary value of pi).

This kind of thing is used often in cryptography to ensure that the keys are created randomly (or as randomly as possible).
 

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Posted by Bob_Scopatz (Member # 1227) on :
 
fugu, it sounds like a good approach.


Minerva...this sounds horrendously complicated -- I mean using the binary value of pi to 200 million regular digits??? Yikes!

But the tests are very clever and simple once you do that conversion, no?

Question, aren't the patterns of bits denoting a single digit essentially non-random? I mean, they specify a digit and not some other digit.

Hmm...

I guess it's okay. I like the brute force method, but then, I'm not a cryptographer.
 

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Posted by fugu13 (Member # 2859) on :
 
Yeah, the binary method would be an extremely elegant choice of rv, because then you should get a simple bernoulli distribution.
 

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Posted by fugu13 (Member # 2859) on :
 
Bob: yes, they do specify a digit and not some other digit, but that's just representation. The "number" is the same whether its in base 10, base 2, base 12, or base 111. None is in any way more fundamental than the others.
 

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Posted by Traveler (Member # 3615) on :
 

quote:

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It's just 37 x 0.17. Can't people do math without calculators any more?

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quote:

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You find it very alarming? Wow. Overreact much?

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Judging from your response I would bet you know all about overreation.
 

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Posted by MrSquicky (Member # 1802) on :
 
Coming soon on Hatrack, you will be able to get members to tie your shoes for you.
 

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Posted by Haloed Silhouette (Member # 8062) on :
 
I prefer using a pencil and paper, Danzig. In 2nd-order stuff in algebra (say, parabulas - that we're going to do very soon, currently we're calculating areas of shapes created by various 1st order graphs and functions). The small things get me confused, and I failed COMPLETELY in three tests because of the plus-minus issues.

That's why I probably won't make it into "5 points"... It all depends on my test result, that I had today.
 

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Posted by Danzig (Member # 4704) on :
 
In second-order algebra, I too would use a pencil and paper, unless I had to get up to get them. But .17 * 37 is mere multiplication. There are no plus-minus issues involved in that one.

Furthermore it just looks cool when you can do mental math faster than someone can type it out on the calculator. It is useful when calculating sales tax while shopping too.
 

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Posted by Papa Moose (Member # 1992) on :
 
Did anyone else who calculated this in their head go .17*37 --> 1.7*3.7 --> (2.7-1)*(2.7+1) --> (2.7)^2-1 --> 7.29-1 --> 6.29? 'Cause, you know, I'm just wondering if anyone else's brain works this way.

--Pop
 

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Posted by Corwin (Member # 5705) on :
 
Nope, I just calculated .17*37, no tricks. It IS somewhat easier if you do it your way, of course, but easy doesn't enter into grown-up life!
 

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Posted by Bob_Scopatz (Member # 1227) on :
 
Actually, I just waited for someone to post the answer.



& fugu, thanks!
 

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Posted by Puppy (Member # 6721) on :
 
The numbers from LOST, run end-to-end, don't show up, either.
 

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Posted by Griffin (Member # 7166) on :
 

quote:

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Originally posted by Dagonee:
Apparently it's 6.

Ain't the Internet grand?

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Assume most of this thread is pointless I was going skip to the last post but this caught my eye.

Thanks Dagonee, I've been looking for a site like this for a long time. It's just good to know the 43653284 digit of pi.

Griffin
 

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Posted by Griffin (Member # 7166) on :
 

quote:

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Originally posted by Papa Moose:
Did anyone else who calculated this in their head go .17*37 --> 1.7*3.7 --> (2.7-1)*(2.7+1) --> (2.7)^2-1 --> 7.29-1 --> 6.29? 'Cause, you know, I'm just wondering if anyone else's brain works this way.

--Pop

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nice

Griffin
 

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Posted by Haloed Silhouette (Member # 8062) on :
 

quote:

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17*37 --> 1.7*3.7 --> (2.7-1)*(2.7+1) --> (2.7)^2-1 --> 7.29-1 --> 6.29

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