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/sci/ - Science & Math

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3157331 No.3157331 [Reply] [Original]

Survey-ish time.

933*27=?

I want you to do the LONG multiplication(with the addition and all that stuff) in your HEAD, no writing or typing anything, and post the time you needed to find the answer.
Dont post the answer though.

>> No.3157337

>I want you to do the LONG multiplication(with the addition and all that stuff) in your HEAD, no writing or typing anything, and post the time you needed to find the answer.
Wow, fuck you with a rake. You think mathematics is about performing arithmetic in your head?

>> No.3157338

>>3157331
25191
fuck you buddy

>> No.3157350

its like being able to memorize order of 4 packs of cards in one minute. the guy who can do it hasnt got a job and failed at life in general.

>> No.3157360

>>3157350
>>3157337
No am just trying to measure which one is the normal.
Not saying that it is important or smth.

Just post the time dummies.

>> No.3157361

>>3157350

Not true.

Fuck off tripfaggot, you are the cancer ruining /sci/.

25191

>> No.3157365

>>3157331
>>3157361
25191, I used a calculator

yeah, yeah, UR STOOPID ON MATHZ sure

sage

>> No.3157369

I generally don't deal with numbers greater than <span class="math">2\pi[/spoiler].

>> No.3157374

>>3157369

I don't believe you never stumbled upon 4\pi.

Also, you're a tripfagging faggot.

>> No.3157379

>>3157374
<span class="math">(2\pi)^N[/spoiler] maybe

>> No.3157384

OP here, it took me 4 minutes to find the answer.

How about you?
Also don't be butthurt.

>> No.3157387

27*3=x
x*10=y
y*30=z
x+y+z=933+27

Thats how I think

>> No.3157394

>>3157387
+ would be * typing is hard

>> No.3157400

>>3157350
Nope. it is been shown that this kind of memory correlates with intelligence very well.
If you can do this then you're smart.

Gtfo of /sci/ dumbfag.

>> No.3157405

20(1000-67)+5(1000-67)+2(1000-67)
Durr

>> No.3157409

>>3157400
>implying intelligence can be objectively defined, and that multiplying in your head quickly = intelligence
Oh boy, here we go.

>> No.3157417

>>3157409
>he can't do it

>> No.3157423

933*27 = (930 + 3)*(30 - 3) = 27900+90-2790-9

That's how i did it.Took me some seconds, i didn't look at a watch because i didn't see OP wanted a time.

Oh and yeah, you only need to memorize 6 numbers, which is a lot less than 4 decks of cards like the tripfaggot idiot in here said.

>> No.3157429

OP here, am i the only one who can do this under 4 minutes?
I gotta be the smartest guy here.

Also, not me but neuroscientists said it.
This is working memory, and working memory is better predictor of intelligence than IQ.

>> No.3157435

>>3157423
No, you have to do it with the conventional/traditional LONG way.

>> No.3157437

>>3157435

But that's stupid.

>> No.3157439

>>3157429
took me 1-2 minutes
didn't really measure it
I would have done it faster if i didn't think this was useless and everybody uses a calculator.

Last time i tried doing this was in elementary

>> No.3157443

>>3157417
He will have kids, unlike you, Foreveralone.

>> No.3157450

>>3157435
So you're telling us to calculate a number using a slower, more innefecient and prone to error method?
You are a disappointment.

>> No.3157454

>>3157450
You're missing the point.
Its not about if you can solve it.
Its about how fast do you solve it using his method.

>> No.3157457

>>3157454
I could solve it faster using the other method, why use this one?

>> No.3157461

>>3157454
why.jpg

>> No.3157462

>>3157454
OP here, at last someone gets it.

Its not about doing your own method or anything like that or the answer itself.
Its about HOW much your brain can store in the working-memory(short term memory).
Do it.

>> No.3157465

Like 933*27 = 933*20 + 933*7 ?

Not that hard either actually.

933*20 = 933*2 and attach a 0 = 18660

933*7 = 7*900+7*30+7*3

Last two operations are basically the same, first one is 7*9 attach two 0's, which gives 6300+210+21 = 6531

Add - done. Only necessary to memorize one number this way.

>> No.3157468

>>3157331
25191

About 17 seconds

>> No.3157478

>>3157462
Wouldn't a better test be "Say 1,2,3,4,5,6,7,2,36,2,6,12,5,1,5673,124&#
44;67 out loud. Wait 10 seconds and then repeat all the numbers you can remember, from the first one to the last one"? At least it's not retarded.

>> No.3157487

Took me about two mintues, but I was off by one hundred.
I was close though.

>> No.3157505

>>3157478
No, because that involves pure memorization.
While with the other you must USE the numbers to calculate.
Thats why it is more important.

>> No.3157527

>>3157505
So by doing things the stupid, retarded, inefficient, slow, prone to failure, dumbfuck, wasteful, incopempetent, fourth grader, long way, I'm actually proving my smarts to you?

>> No.3157550

~45seconds.

>> No.3157552

>>3157527
Not smarts, just your working-memory capacity, which happens to be more predictive than IQ(as read in wikipedia).

>> No.3157554

>>3157552
Oh, wikipedia.

>> No.3157562

>>3157554
>implying your OPINION is better than wikipedia.

You're not even trying.

>> No.3157585

>>3157562
>Implying my opinion isn't better than wikipedia.
>laughingengineers.jpg

>> No.3157612

45 seconds

easy as fuck

>> No.3157617

25,191.
Did it in about 4 seconds in my head.
u mad?

>> No.3157629

25 seconds

but I had to write down the final two numbers on paper, but I added them in my head; 25191

>sure is butthurt math-tarded in here

>> No.3157632

>>3157331
Uh, I don't know?
933/3 = 311

311*9
Oh wait, lol, I'm not allowed to write anything down?
Why would anyone want to do that? Fucking stupid.

>> No.3157642

>>3157632
BECAUSE:
ITS NOT ABOUT FIND THE GODDAMN ANSWER.
Its about overloading your short term memory.
See how much you can do.

FFS read first.
Dumbfag.

>> No.3157651

bleh, ~40 sec or something, but got the correct answer without writing anywhere. I hate mental arithmetics.

>> No.3157656

>>3157642
>>3157642
*finding
Corrected.
>>3157651
Did you do the long traditional way?
Be honest.

>> No.3157658

>>3157632
Not OP, but it is to test your working memory storage capacity (Working Memory Index).
I thought it would be obvious by now.
Also, the part about the duration of the calculation applies to your Processing Speed Index.

Both PSI and WMI are the most highly correlated with g, fluid intelligence and IQ in general.

Therefore, it is safe to say that a person who can do 933*27 mentally and in under 10 seconds would be considered highly intelligent.
Might sound ridiculous to those who are unaware with the human thought process, but those neurological building blocks of the brain have been repeatedly validated by experiments.

(I'm the guy who did it in roughly 4-5 seconds, btw)

>> No.3157668

Everyone by now knows what you wanted to do.

THose are just some guys trolling you.

>> No.3157680

Earlier I mentally calculated that 6^14 = 78,364,164,096 and that 696^4=234,658,861,056 mentally.
It's my hobby.
How do I go as far as working memory goes, OP?

>> No.3157697

>>3157658
but just like everything else, can't you work on this and improve it?

>> No.3157708
File: 46 KB, 960x720, 1280883596341.jpg [View same] [iqdb] [saucenao] [google]
3157708

>>3157400
>it is been shown

>> No.3157714

>>3157697
You could, but your rate and limit of improving are once again determined mainly by your WMI and PSI.
It is very much possible that some people may dedicate their entire lives to improving themselves at a certain field, while others who were born with far higher WMI and PSI values will - as a starting position - be able to perform far higher than the rest at the same tasks.
It's all about genetics, and there is nothing that can be done about it.

>> No.3157716

>>3157708
Actually he has it right.
So double fail to you.

>> No.3157724
File: 18 KB, 130x179, 1292281169715.jpg [View same] [iqdb] [saucenao] [google]
3157724

>>3157716
>it is been shown

>> No.3157726

>>3157716
It's "it has been shown". "is been" has contradicting tenses.

>> No.3157727

>>3157714
Practice can be done.
Those things area easily improved with practice.

>> No.3157734
File: 20 KB, 464x518, 12665234523872.jpg [View same] [iqdb] [saucenao] [google]
3157734

>it is been shown

>> No.3157737

>>3157714

I believe very much, also because of personal experience, that the most important aspect having an influence on this is the environment one has up to the age of 6 or so.

>> No.3157739

>>3157727
>Easily
Read again, it was very explanatory.

>> No.3157754

>>3157658
wait.
Let me ask you, did you use the whole traditional way?

Like having the two series one below the other and then add them together to find the answer?

Bc it is impossible to do that in 5 seconds.

>> No.3157761

>>3157737
Possible that the influence of one's environment on the construction of one's neural pathways might be noticeable (though not by much, and doubtfully up until the age of 6 and not far earlier), however the range of influence is determined by genetics, specifically, the brain's susceptibility to environmentally-induced modeling and remodeling of it.
Again, WMI and PSI will prevail, always.
There is little to no debate on that fact in the neuroscientific community.

>> No.3157770

>>3157754
It very much is.
I simply see the patterns while I work with them, and as such I reach these solution rapidly.
27*933 = 27*(900+30+3) = 24,300 + 810 + 81 = 24,300 + 891 = 25,191.

>> No.3157781

>>3157770
Well you should try the actual traditional way.
No patterns or other shortcuts.

Just do:

933
x 27
-------
xxxx
+yyyy
---------
zzzzz

You have to keep in mind all the x and y etc.
One by one.

>> No.3157783

>>3157770
Though my favorite method would be 27*900 + 27*33, which is 24,300 + 27*33 = 24,300 + (30-3)*(30+3) = 24,300 + 30^2 - 3^2 = 24,300 + 900 - 9 = Either 25,200 - 9 = 25,191 or 24,300 + 891 = 25,191.
Depending on my mood, of course.
However OP specifically asked that I won't use any method, so I didn't.
I'm also this guy:

>>3157680

>> No.3157787

>>3157781
Thing is, when you ask me what's 27*9 I will almost immediately inform you that it is 243.
I really won't have to compute it as 180+63.
I skip a few steps because I don't need them, not as a special method. Is it wrong?

>> No.3157789

>>3157761

I could multiply 3digit numbers from some time up to the age of about 16. I also had almost perfect memory.
My then girlfriend and some other people were generelly afraid of my memory, so i did the best i could to get rid of it and it worked.

>> No.3157793

http://www.youtube.com/watch?v=OI67pzdbVJk

>> No.3157802

>>3157787
It is about holding up as many numbers you can while operating on them.
So, even if you know the result of 2 or more digits you still do it one by one.

>> No.3157807

>>3157789
There are several points about that story that make it seem untrue, though I won't doubt you.

>> No.3157810

>>3157783
Good but i suggest you try this:
>>3157781
And tell us the timing.

You will be surprised how hard it is.

>> No.3157813

Took a little over a minute.
933*3=2799
27990-2799=25191

I honestly can't do the long multiplication way in my head anymore. Used to train for this shit back in elementary school, but calculators managed to dull my brain for the past decade.

>> No.3157822

>>3157807

I promise you it's true. I know that doesn't mean much on the internet, but why would i lie.

I regret it very much.

>> No.3157828

>>3157822
Whoa, dont know if troll or not but i would kill for that kind of memory/ability.

And you stopped cause your ho wanted to look cool?

I would rage hard and kill people in between.

>> No.3157830

>>3157761
>>3157761

I fucking hate the WMI and PSI on WAIS, because it is included in full scale IQ. This implies that they are aspects of intelligence.

I see it as ridiculous as predicting basketball performance with height. Many, many people have significant deficits in one or both of these areas, especially within the gifted population (130 IQ or more). I'd need to see the results replicated, but a gifted program was criticizing the WAIS IV's full scale IQ of being a poor measure of giftedness due to processing speed and working memory indexes correlating 34% and 60% to full scale IQ respectively.

>> No.3157832

>>3157813
Nope try this:
>>3157781
Then it will be legit.

>> No.3157840

took me about 40 seconds.

i basically do it the 'long division' way but i do it where you just take each multiplication at a time and keep a running total, so like 900 * 20 + 900 * 7 etc., i find it quicker. order of how i multiplied them togethar doesn't matter.

>> No.3157915

>>3157830
Hardcore liberal detected.

>> No.3157938

I have yet another limit question:

as x --> 0, (ax + b)^(1/3) - 2 / x

Find the values of the constants a and b such that the limit = 5/12.

>> No.3157972

933*30= 27 990

933*3= 2799

27990-2799= 25 191

>> No.3157980

>>3157938

Not possible because of the 2/x

>> No.3157984 [DELETED] 

891 +
180,000
63,000

25191

2 minutes.

>> No.3157986

>>3157972
wrong.
wrong.
You do the same mistake as everyone does.
Look here:
>>3157781
And do that mentally.

>> No.3158030

I took more than a minute and I failed.

>> No.3158045

I failed to do this part in my head, a combination of apathy exacerbated by memory problems were the cause.

27990-2799 = 25191

>> No.3158051

Around 30 seconds.

>> No.3158066

About 2 minutes

>> No.3158074

27*933
27(900+30+3)
27*900 = 24,300
27*30 = 891
27*3 = 81
24,300 + 891 + 81 = 25,191

There is no way other than using a calculator that is faster.

>> No.3158112

>>3157986

Just did, took the time since you last posted for me

>> No.3158117

>>3158074
27*30=810

fix'd

>> No.3158119

Russian multiplication , how does it work???

>> No.3158120

>>3158074
27*933
= 30*933 - 3*933
= 27990 - 2799
= 25191
I have to carry twice, once for "30*933" and once for "27990 - 2799."
also, cool math bro.

>> No.3158125

>>3158112
I know, its completely mindfuck doing that long way.

>> No.3158129

>>3158074
See:

>>3157781
>>3157781
>>3157781
>>3157781
>>3157781
>>3157781
>>3157781
>>3157781
>>3157781
>>3157781
>>3157781

>> No.3158138

OP HERE YOU DO THIS:
933
x 27
-------
xxxx
+yyyy
---------
zzzzz
NO SHORTCUTS OR OTHER METHODS.
ONE BY ONE, EVERY DIGIT.

>> No.3158145

>>3157409

Scientist:
>"we've found that there is a high correlation between speeding and fatal car crashes"

You:
>HE THINKS SPEEDING = DEATH WOW WHAT AN IDIOT CORRELATION DOESN'T MEAN CAUSATION OMG LAUGHINGGIRLS.JPG

>> No.3158160

25191
like a minute. very surprising seeing as how i suck a arithmetic.
not that it matters though

>> No.3158185

>>3158160
The addition is what got me.
I did the whole 20*933 + 7*933
18660 + 6531 and i had to align them in my head.
Took 2 seconds for the first part, 60 for the second

>> No.3158192

Okay, new challenge.
Mentally compute 733^4.
No external sources, and state how long it took you.

>> No.3158199

>>3158192
It took me around 24 seconds.

>> No.3158230

I have yet another limit question:

as x --> 0, ((ax + b)^(1/3) - 2) / x

Find the values of the constants a and b such that the limit = 5/12.

>> No.3158244

>>3158230

Still won't work, because of the 2/x

try harder

>> No.3158260

lim x->0 sin(x)/(1-cos(x))?

>> No.3158293

>>3158260

That's better. Multiply by 1+cos(x), get

lim x->0 (sin(x)+sin(x)cos(x))/(1-cos^2(x)) = lim x-> 0 (sin(x)+sin(x)cos(x))/sin^2(x)

= lim x-> 0 1/sin(x) +tan(x)

= \pm infinity, depending on where you approach 0, so the limit does not exist.

>> No.3158300

>>3158293

Ooops, cot(x) instead of tan(x) of course.

>> No.3158349

>>3158300
Sorry, I forgot a term.
lim x->0 (x-sin(x))/(1-cos(x))?

>> No.3158459

>>3158244

What? It has to, it's on a past exam.

>> No.3158465

>>3158459

That is, I know I can't just plug in and go, but there has to be a method (a non lhopital method, the question explicitly states) that works.

>> No.3158479

>>3158459
>>3158465

You can write that equation as [...] - 2/x, he 2/x term always makes the limit non-existent.

Unless you meant lim x-> infinity of course.

>> No.3158517

>>3158479

That's why I modified my second posting - the 2/x term you're talking about is a misinterpretation. What it's supposed to say is [sdfasdg] / x. That whole part before the / is all divided by x, not just the two. That may help?

>> No.3158552

>>3158517

Not really. The rest is still of the form (a+b), so that

(a+b)/x = a/x + b/x

where b is 2.

>> No.3158589

We must be missing something though, (ax + b)^1/3 - 2 all over x = 5/12. That's what we have down right?

Thanks for the help anyways if this post was just reiteration though.

>> No.3158637

>>3158589

((ax + b)^1/3 - 2)/x = (ax + b)^1/3 / x - 2/x

There must be something wrong.

>> No.3158650

>>3158637

What if we think about it like an equation? Multiply both sides by x (or x/x if need be) and get just the numerator times x = 5x/12x or 5x/12 depending on what we decide?

>> No.3158661

can i do factoring instead, like multiplying by 3 three times?

>> No.3158669

25191. Took me about 2 minutes. What I did was do 1000-933 (67), multiplied that times 27 (that took a while, I added by fours in my head) and then subtracted 27,000 by that.

>> No.3158685

933 * 3 and 933 * 30 (second obviously follows easily from first, and first can be done with very little carrying.

then subtract former from latter.

>> No.3158712

25191

2 minutes, 14 seconds according to a stopwatch.

>> No.3158714

26781

>> No.3158718

>>3158650

No, because the limit doesn't exist.

Setting it equal to 5/12 doesn't make it an equation because the term after the limit is still undefined because of the 2/x.

That would be like dividing by 0.

>> No.3158764

933/3=311
27/3=9
311*9=3110-311=2799
2799*9=27990-2800+1=25191

>> No.3161157

Bump for more anons

>> No.3161753

25551

nice number lol

>> No.3161784

I do it by saying that 933*27 = 311 * 3 * 3^3 = 311 * 3^4 = 311*81

300*81 = 24300
+ 810
= 25110
+ 81
= 25191
About 25 seconds

>> No.3161814

Couldn't do it, I can make the calculations but I can't remember them long enough so I gave up.

>> No.3161860
File: 8 KB, 248x250, 1304382230157s[1].jpg [View same] [iqdb] [saucenao] [google]
3161860

>>3161784
>Takes over 15 seconds

>> No.3163324

>>3157331

>> No.3163354

>>3161860
>>3161814 here, it's funny how you laugh at him but not me

Please laugh at me to restore balance to the universe.

>> No.3163380

Doing it using the intuitive method that requires less working memory took me 40 seconds. Doing it using the long multiplication method took me 25 seconds. U mad, neurologists?

>> No.3163401

933*27 = 933*30 - 933*3 = 900*30 + 33*30 - 900*3 - 33*3 = 27000 + 990 - 2700 - 99 = whatever cause I'm not supposed to post it.

Took maybe 10 seconds?

>> No.3163481

Circle jerk thread.

>> No.3163559
File: 4 KB, 168x214, 1304281825146.jpg [View same] [iqdb] [saucenao] [google]
3163559

>short term memorization
>intelligence

>> No.3163579

2 minutes, including the minute and a half thinking about how I am such a failure for not having the answer by 15 seconds.