/sci/ - Science & Math

None

>>5495506
1=0.999...9954

Whats a progressive set to answer it?

You have one hour to aquire your Internet™
>thecaptcha

What's three trees?

How many coins are in my pocket?

>>5496499
Zero. I'd hear them jingling.

>>5496503
Is zero a number?

An old man wakes up at 3am to go feed the sheep. He has 283 sheep and each one takes a half hour to eat. How long before all of the sheep have eaten?

>>5496560
you don't expect anyone to answer 141 1/2 hours do you?
i guess it'd be done in 1/2 hour-1 and 1/2 hour depending on how he feeds them, as it's not certain he will get to feed them all at once

>>5496560
Well he's an old man, so I guess he'll just stay in bed taking his medicine istead of feeding those gay sheep.

>>5496523
It depends on which numerical system you look at. Arabic numerals? Yes. Babylonian numerals? No.

>>5496565
Maybe about 10 minutes. I don't see why he would have to sit there and wait for the sheep to eat.

>>5496573
>How long before all of the sheep have eaten?

A mathematician has a dollar bill, a five dollar bill, and a twenty dollar bill in his pocket. If you make a true statement, he will give you one of them at random. However if you say a false statement, you will receive nothing.
What should you say in order to have a 100% chance of getting the twenty dollar bill?

A census taker approaches a house and asks the woman who answers the door "How many children do you have, and what are their ages?"

Woman: "I have three children, the product of their ages are 36, the sum of their ages are equal to the address of the house next door."
The census taker walks next door, comes back and says "I need more information."
The woman replies "I have to go, my oldest child is sleeping upstairs."
Census taker: "Thank you, I now have everything I need."
What are the ages of each of the three children?

inbefore people look it up

c'mon, there's no way an old guy could eat that many sheep

>>5496560

Half an hour, what kind of fucking idiot would go around feeding the sheep one by one and watching them masticate and shit?

>>5496583
2, 2 and 9

>>5496589
>>5496583
Why can't it be 3, 3 and 4

>>5496578
I will recieve the 20 dollar bill?

>>5496607
He gives you nothing because that is now a false statement. Assume the mathematician is a greedy son of a bitch.

>>5496607
>>5496611
wait no got confused. "I will get the $20 or nothing". That should work....I think

>>5496578

How many questions are you allowed to ask/statements allowed to make? Because if you're only allowed to make 1 statement, that's (100% chance of getting the 20 bill) is impossible.

>>5496578
"I will receive $20 or I will receive nothing."

>>5496617
>>5496677
correct. It might be worth noting that that is not the only solution.

>>5496697
"I will not receive $5, nor will I receive $10.

>>5496697
i will not receive a $1 or a $5

>>5496700
>implying there is a $10

>>5495506
>Can we get some math riddles?
sure. more a puzzle than a riddle. still counts?

you have 8 8's in a row:
88888888

putting only '+' signs in between the numbers, make it add up to 1000.

no google

>>5496700
>>5496701
statement might be false, so you receive nothing

>>5496702
thats why he wont receive it =p

>>5496706
888+88+8+8+8

>>5496704
888+88+8+8+8

i don't even have to check

it's the only way possible (except for order)

>>5496706
if i receive nothing then the statement is true you retard

>>5496706
If the statement would be wrong he would receive nothing, which would Marke hie? statement trug.

>>5496708
>>5496709
yeh, nice.
it's an old one; too well known i think.

i'll try and remember a harder one

>>5496712
yeh, but the question says he picks a note at random. he doesnt know what he gives you
>here you are.. oh shit, thats a fiver! you're statement was a lie! *SNATCH* I'LL HAVE THAT BACK!"

>>5496720
then the question is silly as he can't act based on what you say, and you'll just get a random not whatever

it's because OP badly phrased it, the original version is not "at random"

>>5496720
By your reasoning the puzzle is impossible then, by definition if he is recieving the notes at random, then he can't get 100% the $20 ever anyway.

What the original poster presumably ment is that if the questioner gives a true statement, the mathematician gives him a note from the ones that don't falsify the statement

>>5496720
Which makes it true again, here's a possible 20 or repeat. How the fuck is it supposed to work with the other solution?

>>5496723
oh ok. that works too then.

new puzzle, similar to the last one.

you have all the digits from 1 to 9 in a row:
123456789
adding mathematical symbols anywhere you like, make the result exactly 100.

plus, minus,whatever, even indices if you like (in fact...bonus points if you can manage that)

only add in the symbols. you cant rearange anything.

1
11
21
1211
111221
312211
13112221
1113213211

complete the sequence and shut the fuck up if you know it already

>>5496757
31131211131221

another oldie goldie
/sci/tards will be pretty familiar with that :)

>>5496732
123 - 4 - 5 - 6 - 7 + 8 - 9

Easy

>>5496732
>bonus points for increasing complexity of a solution
>not giving bonus points to the simplest solution

>>5496764
yeh, theres multiple solution IIRC

another one then:
i have 100 lightbulbs in a row.
i go along turning all of them on (coz i'm a sad fuck like that =p)
then i go along and press the switch on every second one. so half the lightbulbs are off, and half are on, like so:
XOXOXOXOXO...

then i go along and press the switch on every 3rd one. so ones that are off turn on, and ones that are on turn off.

then every fourth one
then every 5th one
etc.

i keep going untill i have to turn the switch on every hundreth one (so, i just turn the last one on/off)

...how many lights are on when i'm done?

>>5496780
This is a good puzzle. Much better than that "insert symbol" crap.

>>5496780

10

>>5496795
Yup.

>>5496795
>>5496798
Expain?

>>5496803
The only numbers with an odd number of divisors are square numbers.

>>5496803
Think about how many times each button would be pushed.

>>5496795
yep. nice.

ok, one more.

i have 10 cards with the numbers 1 to 10 written on them. i shuffle them ,and pick out 4 of them at random.
i call two super-genius mathematicians into the room, and i whisper the sum of the 4 cards i chose to one of them, and the product of all of the 4 cards to the other.

both of them are perfectly logical, and they both know that the other one is as well.
the only thing they are permitted to say is how many numbers they think they know, to the other one.
if they can work out what the 4 numbers are, then i set them free. otherwise, i execute both of them.
person A: i know zero numbers
person B: i know 1 number
person A: now i know 2 numbers
person B: now i know all of them.

and person B tells me, and is correct, so i set them free.
what were the numbers?

>>5496808
0 is square, but doesn't have an odd number of divisors

>>5496808
Is this a well known fact? I only just learnt this and I've done a fair bit of maths at uni :/

>>5496818
there isn't a 0th lightbulb!
the first one is number 1!

>>5496821
You might not have known it, but could you have answered the question "What kind of numbers have an odd number of divisors?"

>>5496821
Its proof requires only knowledge of the definition of a divisor. So basically it can be known to an elementary school kid.

>>5496826
I hope so

>>5496823
i wasn't speaking in the context of the lightbulb question, but addressing the statement at >>5496808 generally

>>5496821
yeh.
think of a number like 24
i'd switch it on and then off on cycles 2 and 12 (coz they multiply to make 24)
and then on and off again on cycles 3 and 8.
then on and off again on cycles 4 and 6.

so it stays off.
coz it aint square
wheras a number like 9.
i turn it on and then off on cycles 1 and 9.
but i turn it on cycle 3 as well.
so it stays on at the end.

>>5496815
Did you tell the product to person A or B? Or is that part of the riddle?

>>5496834
oh yeh, sorry
i told person A the sum.
i told person B the product.

i whispered to both, and the other one didnt overhear.
hint: so, knowing just the sum, you can't know the numbers. so you know the numbers arnt 7,8,9,10, because that has a unique sum of 34, which doesnt work for any other combination of numbers. and person A, being a perfect with logic, knows this.

>>5496830
In the integers 0 has infinitely many divisors. Just define infinity to be odd.

>>5496808
2*3*5 = 30 =/= x^2? What am I missing here?

>>5496841
if you define infinity to be odd you get contradictions. like odd + odd = even no longer applies (of disjoint union of sets and the sum of their cardinalities)

you cannot just add definitions to math unless they are consistent with the rest of math

>>5496843
Not prime divisors, all divisors. 1,2,3,5,6,10,15,30 are all divisors.

>>5496815
I think 2,2,2,2 works.

>>5496843
>What am I missing here?
1, 6 and 30

>>5496843

>>5496849
Never mind, you only have 1 of each card.

>>5496849
the number 2 only appears on one of the cards. once i choose a card, i set it aside, and choose 3 more from the cards that are left (that all have different numbers)

>>5496847
ah, ofc. thanks.

Is EK setting all you faggots straight in here?

I have a question with 4 answrs, each has a 33.6% chance of being right. How can I be right if it's just a geuss?

>>5496932
>setting them straight.
nah, being an engineer is an acceptable lifechoice in the modern age, people have come to except them now =p

also, anyone got anywhere with my last puzzle? the 4 number cards one?

>>5496935
>except

>>5496945
*accept.
fuck you, this isnt a spelling bee

>>5496935
>>5496963
>>5496823
>>5496761
Why do faggots like you always post pictures when they reply?

>>5496815
Look at ways of expressing the same number in two ways as a sum of numbers on four cards, where the corresponding card sets are disjoint.
2. Prime factorization.
3. Keep thinking.

Here's one from the professor

>>5496986
just $20, i think
the clerk gives him $50 for the bill.
he give the woman her $20 change, and keeps $30 for the price of the shoes.

then he gives $50 to the clerk, because the bill was counterfit. so he's on -$20

so he's down $20, and also missing the $30 shoes.

so in total value of money+products, i guess he's down $50.

>>5496997
You didn't account for the value of the shoes, it's -50
She gives me a counterfeit bill I have $0
I give her shoes -30
I gain 50 20
I give her 20 change 0
I repay the full 50 to the guy who gave me change -50

>>5497002
>so in total value of money+products, i guess he's down $50.
read more

>>5496969
Because newfags gonna new. Newfags think 4chan is the site for le epic maymays and they think every board is /b/. "lol hurr durr just because we can upload pictures I must do it /b/cuz every post must have a pic, no matter how unrelated and off-topic." At least they make it easy to detect that they are underaged.

>>5496986
the store money is irrelevant to the clerk. he's down 50 as he gave the other store 50

>>5497019
i'm 37, been on /sci/ about two years, almost never go to /b/ or anywhere else, and i post pics

u mad?

>>5497019
As if a tripcode wasn't enough.

>>5497024
Haha, 37 fucking years old. Have you ordered your coffin yet?

>>5497033
>43 yr old detected

>>5497024
You are clearly not 37, stop lying. I can imagine though that you will still be here two decades later when you actually turn 37.

>>5497037
>clearly
implying anyone can prove it either way

>>5497037
>>5497035
>>5497033
half of 4chan outside of /b/ is sad old people

i'm surprised you need this pointing out

>>5497043
34 yrs Checkinin

>>5497043
>>5497045
nope

>>5497051

if you are young, get out while you still have the strength

otherwise you are here forever

>>5497043
I'm 28. Does that count?

>>5496986

I can't help but come to the conclusion that the shoe store lost 100 dollars.

30- for the value of the shoes, plus the 20 dollars in change which = 0 because the bill was counterfeit. He is down 50 dollars now because he broke the change with the neighboring shop but the shop owner demands to take another 50 dollars to make up for the counterfeit bill.

-50-50= -100.

Am I retarded or did I just miss some critical detail somewhere?

>>5497283

Or it could be -$80, assuming the shoe store clerk kept the 20 dollars in change from the first transaction.

>>5496986
20

There was one chicken and one egg. If the egg hatched, how many chickens were there?

>>5497386
What came first - the chicken or the egg?

>>5497389

Chicken. The egg is the chickens son.

>>5497403
But where did the chicken come from?

>>5497405
Science

>>5497411
Where did science come from?

>>5496821
If you take any non-square number, and find a factor of it, there will be a unique, corresponding factor. So, for any non-square number, there is an even number of factors.

This is true for most factors of a square number - except for the square root. The corresponding factor of the square root is just the square root. So you would add 1 to an even number (the other factors, that do have a unique match), and get an odd number.

>>5497412
Math

>>5497420
Math is just applied philosophy.

>>5497421
Where did philosophy come from?

>>5497438
Hatched from the egg.

>>5496571
Incorrect. 0 is a placeholder when with numbers and a symbol by itself.

>>5497389
the egg. Do you even evolution?

>>5496757
>1
>11
>21
>1211
>111221
>312211
>13112221
>1113213211
>13112221
>312211
>111221
>21
>11
>1

You are on an island where everybody either always lies or always tells the truth. You meet a man who says, "Either I'm a liar, or 2 + 2 = 5." What would you conclude?

>>5497731
that he is a liar
T||F => F
doesn't matter which one is a lie

>>5497739
Shit, beat me to it.

But would the usage of the word "either" make it an xor, rather than just an or?

>>5497745
no lol wut

>>5497752
An xor is an exclusive or.

T xor T = F
T xor F = T
F xor T = T
F xor F = F

Basically, one, and only one, of them can be true. If he had just said "I'm a liar, or 2 + 2 = 5" then it would clearly just be a logical or. But he threw the "Either" in there.

>>5497770
I know what xor is, either is a grammatical pair with or.

idk what would go with xor though

niether nor?

>>5497777
also dem quads

>>5497739
>T||F => F
Hurr

31131211131221

>>5496757
31131211131221

>>5497739
No, this is completely wrong.

We know the second statement is obviously wrong, so we have:

T || F = T
F || F = F

In English, those are:
If he always lies, he told the truth (obvious contradiction).
If he always tells the truth, he lied (obvious contradiction).

Nothing can be concluded.

>>5495506
What number am I thinking of?

>>5498020
69 dude!

>>5496585

Well that's how I feed my sheep and I'm not going to change now.