# Calvin Lin's messageboard

Moved: Calvin Lin's Messageboard-2.

This is now locked as it has too many comments.

Hi guys! You can leave messages for me here.

Does anyone know of a good contradiction that uses $\pi = \frac{22}{7}$? If so, send me a message!

One that I found is $0 < \int_0^1 = \frac{ x^4 (1-x)^4 } { 1+x^2 } dx = \frac{22}{7} - \pi = 0$. The integration does take some work to show.

Note by Calvin Lin
7 years, 1 month ago

1 vote

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Does any know of a good contradiction that uses $\pi = \frac {22}{7}$?

By Euler's formula, $e^{-iy} = \cos (y) + i \sin (y)$

Let $\large x = i^i \Rightarrow \ln (x) = i \cdot \ln (i) = i \cdot i \cdot \frac {\pi}{2} \Rightarrow i^i = e^{-\pi/2}$

Similarly, let $\large x = (-i)^{-i} \Rightarrow \ln (x) = -i \cdot \ln (-i) = -i \cdot i \cdot -\frac {\pi}{2} \Rightarrow (-i)^{-i} = e^{-\pi/2}$

So $\large i^i = (-i)^{-i} = e^{-\pi/2}$

Suppose $\large \pi = \frac {22}{7}$

$\large i^i = e^{-11/7}$

$\large i^{7i} = e^{-11}$

$\large (i^7)^i = e^{-11}$

$\large (-i)^i = e^{-11}$

$\large (-i)^{-i} = e^{11} \ne i^i$ which is a contradiction. So $\pi \ne \frac {22}{7}$

- 7 years, 1 month ago

But ${ (-i) }^{ -i }={ i }^{ i }$, so I'm not sure this makes for a contradiction.

- 6 years, 11 months ago

Yes indeed, $(-i)^{-i} = i^i$, I have also shown that because they both are equal to $e^{-\pi /2}$, then the last 5 steps of my proof shows that $e^{11} = e^{-11/7} \Rightarrow 11 = - \frac {11}{7}$ which is absurd.

- 6 years, 11 months ago

Oh, there you go!

- 6 years, 11 months ago

Calvin Sir,what is the field of mathematics that you do your research on??

- 7 years, 1 month ago

@Calvin Lin I want to know too?

- 6 years, 9 months ago

@Vishnudatt Gupta Please refrain from posting solutions which are directly copied off of another, or just a statement of the correct numerical answer. We have removed the solutions that you wrote in the past 5 days. If you continue to do so, we will take further action.

Staff - 6 years, 12 months ago

@Calvin Lin - I need a good solution for Alex's Simple Division problem. Whereas A person named @ saurabh malik (14 years) has just copied and pasted the answer and written it as a solution and has also got upvotes. You must take stern action against him. He is also spamming lot of solutions with an anagram puzzle. He NEVER writes a good solution. Hope you will take stern action against him.

- 6 years, 11 months ago

@Calvin Lin I have some questions for you....

1. Do you work from home or go to a Brilliant headquarter daily to work?

2. Did you find Brilliant or Brilliant found you?

3. What did you do before you met Brilliant?

4. Could you please suggest me some good learning material for maths?

- 6 years, 11 months ago

1. Most of us (me included) are based in San Francisco, and do meet at an office. It makes for easier discussion of ideas.

2. I knew Sue from our days at University of Chicago. When she had the idea for this website, she approached me as she knew of my interest regarding reaching out to and educating talented students.

3. I was an options trader.

4. That would obviously depend on your ability level. Given that you're Level 3-5 in most topics, the current practice section is out of your reach. However, I'm building out the Olympiad Algebra section, which would become a valuable resource for learning how to apply different skills and techniques.
I would encourage you to read my sets of notes like Olympiad Algebra. Over time, I'd also be fleshing out them individually, like in the sets Telescoping Series and Recurrence Relations Made Hard.

Staff - 6 years, 11 months ago

@Calvin Lin I reported a couple of problems, that I faced while using this site, to the email address mentioned on the Help page, but so far I've got no response regarding the problems. What do you suggest I should do?

- 6 years, 9 months ago

The best approach would be to report the problems directly from the page itself, by selecting the "dot dot dot" menu in the lower right. This way, the author is aware of your report, and can correct it accordingly. You should also look at the solution discussion to see how others approached the problem.

Emails that you send eventually make their way to me. I then report the question, with the information that you provided. You can speed up the process by reporting it directly.

We do not respond to reports directly. If the answer gets updated, you will receive an email if you gve the correct answer. If the question was edited for clarity, we do not send out emails. If your report is in error, you will not be informed.

Staff - 6 years, 9 months ago

@Calvin Lin The problem isn't with some question. I posted a solution to a problem but after realizing that I had made a mistake, I deleted it. But now, I'm unable to post the correct solution to the same problem as there is no box available to write the solution into.
Also, I created a set,by mistake, a few days back and now I don't see a button to delete it.

Here's the link to the problem: [https://brilliant.org/community-problem/cyclic-equations/?group=x4I7elL52HYa]
Here's the link to the set that I want to delete: [https://brilliant.org/profile/rakshit-yejciq/sets/unsolved/]

- 6 years, 9 months ago

1. You can only submit 1 solution, even though you deleted it. In future, you should edit your solution instead.

2. You are unable to delete sets as yet. What you have done is a good alternative.

Staff - 6 years, 9 months ago

@Calvin Lin So, is there no way now by which I can post my solution to the problem?

- 6 years, 9 months ago

@Sharky Kesa How Do You Solve This is an interesting question which echos the discussion that I had with @Finn Hulse in The Threes, where a kind of size argument is needed to prove that $x = y$.

Can one of you add a correct solution to this problem?

Staff - 7 years, 1 month ago

Yes you did...

- 7 years, 1 month ago

My solution isn't complete. It needs an argument about why $x = y$. The problem is obvious after that.

Staff - 7 years, 1 month ago

I have written a complete solution for the problem.

- 7 years, 1 month ago

What math class are you in, Sharky?

- 7 years, 1 month ago

I am in Year 7 and I am with the rest of my core class, but I get way more advanced work to do.

- 7 years, 1 month ago

So like, trig? Also, are you following me?

- 7 years, 1 month ago

A bit like trig except slightly more advanced. Its not calculus. I learnt calculus mainly on brilliant. And yes, I am following you.

- 7 years, 1 month ago

Hey @Sharky Kesa, would you try & give IIT-JEE? It would be fun if Brilliant has its own All India Rank 1!!!!

- 6 years, 8 months ago

I probably would do it but AIR 1?! I would be nowhere near that!

- 6 years, 8 months ago

@Sharky Kesa, think again!

- 6 years, 8 months ago

I think I would just make it to top 1000 but nowhere near top 100. The amount of silly mistakes alone...

- 6 years, 8 months ago

YES! Hey, congrats on making the "Who to follow" page. You must be really happy! I was kind of disappointed with the turnout, though. I didn't make it... :( Why do you think that is?

- 7 years, 1 month ago

Thanks, and yeah, I feel really happy. I reckon you didn't make it is because you make loads of awesome notes, although your problems are a good challenge.

- 7 years, 1 month ago

Wait... What? You think I didn't make it because my problems are a good challenge? :O

- 7 years, 1 month ago

No, it sounds weird but I think you didn't make it because your notes and problems themselves give you high publicity. You don't need to be on it to get followers. The stuff you put on gives you way more followers than what most people get.

- 7 years, 1 month ago

Hmm. I am the only person ever to exceed 700 followers without being on that list... but seriously, that simply means I am a legit person to follow.

- 7 years, 1 month ago

@Finn Hulse I'm not on the Who to Follow page and I have approximately 850 followers :P

- 6 years, 9 months ago

Mate, this was a long time back. He reached 1900 followers without getting on the Who to Follow page. :P

- 6 years, 9 months ago

Solved all, made one careless mistake on Q28. I put 32 instead of 48...

- 6 years, 9 months ago

Hey Victor, aren't you getting a medal? I am and I got question 28 wrong.

- 6 years, 7 months ago

That's 8 marks :( But I think I got the rest correct. I checked with some of my friends. And Q30 was easier than I thought it would be :P

- 6 years, 9 months ago

@Sharky Kesa

- 6 years, 9 months ago

What answer did u get in the 30th one?@Victor Loh I got 598!

- 6 years, 9 months ago

598 is correct.

- 6 years, 9 months ago

@Sharky Kesa This is also what I got. :D

- 6 years, 9 months ago

I agree... SImple application of variables and... TADAAAA 598 you go! (:

- 6 years, 8 months ago

Same.

- 6 years, 9 months ago

What about the 26th?Think it's 904..

- 6 years, 9 months ago

Which one was that again?

- 6 years, 9 months ago

I think I got 48. Yeah, Q30 was pretty simple; it was my favourite however.

- 6 years, 9 months ago

How was the Australian Maths Comp?

- 6 years, 9 months ago

Oh dude that's nice! Good job! :D

- 6 years, 9 months ago

@Thaddeus Abiy Nice set of CS problems. How did you decide what problems to include?

Staff - 7 years, 1 month ago

- 7 years ago

Thanks. There really wasn't a criteria though..I just put my all my favorite into one big set.I might have missed some other problems but those were the most I had fun with since brilliant CS started.

- 7 years, 1 month ago

Hi, this question just pop-up in my mind. What are the difference between you and the Best of NT, Algebra, etc.? Are there other people to control the Best of's?

- 7 years ago

- 6 years, 10 months ago

@Calvin Lin I need a solution to the problem "Mod AP"?I can't understand how can it be solved??

- 6 years, 9 months ago

It has been reported multiple times, it probably is wrong.

- 6 years, 9 months ago

The question was flagged because it allows for multiple answers.

I see that you are listed as one of its recent solvers, so you should add your solution.

Staff - 6 years, 9 months ago

Well I just guessed it and got it correct! Instead of directly looking at its solution,i just gave it a try and got it solved!:D

- 6 years, 9 months ago

@Calvin Lin , could you please do a note on Zsigmondy's theorem? I'd really love that!

- 6 years, 9 months ago

- 6 years, 9 months ago

yeah me too!!

- 6 years, 9 months ago

How can we put an image while posting a solution???

- 6 years, 9 months ago

Yes, I'd like to know how so I can post some screenshots of graphs.

- 6 years, 9 months ago

You can use markdown code.
"! [title] (url link)", with no spaces in between, will display the image in the url link.
"[title] (url link)", with no spaces in between, will hyperlink to the site.

Make sure your url link is to the image itself, i.e. it should end with jpg / gif / png.

Staff - 6 years, 9 months ago

Thanks sir!!

- 6 years, 9 months ago

Thanks for resharing my problem, Calvin :)

Sorry if you get this a lot and it's kinda spammy, but I wanted you to know I appreciate it, anyway.

Really looking forward to physics practice sections. Keep up the great work.

Cheers

- 6 years, 9 months ago

You have it now!

- 6 years, 7 months ago

YEAH! Lol but I won't be needing them anytime soon. AP Physics is loading me with rigor >.<.

And wow, looking back from now, when I posted this comment I had 7 followers... Calvin's reshare of my "Big problem, Small solution" really got the ball rolling. What a right person in power can do...

- 6 years, 7 months ago

Hi Calvin. Sorry to bother you with this, but I have a concern with the diagram that has been added to a question of mine. I always appreciate when diagrams are attached to my questions by the moderators, but in this case it does not match the parameters of the question and may prove to be a bit confusing to some. If at all possible, could a more accurate representation of the circles in question be supplied? Thanks for your help.

EDIT: Oh, I just checked the problem again and the diagram had been changed. That was a fast response! Thanks. :)

- 6 years, 5 months ago

You're really great , Sir Calvin Lin! What do inspired you to educate talented students?

- 6 years, 5 months ago

I've always been interested in working with talented students and helping them develop further. They are often motivated to pursue their interests, and also see great value in devoting the time and energy that is required of them. Sue was aware of my interest, and approached me to help out when she was starting Brilliant.

I think it is extremely worthwhile to work on problem solving skills, and to develop cognitive pathways that help you approach and think about issues. This skill is much more widely applicable than memorizing stuff that's in a textbook, especially in the workplace. I am excited to be working on Brilliant, to help provide a good educational resource that is easily accessible to all around the world.

Staff - 6 years, 5 months ago

@Calvin Lin, can you tell me how to put 'image credits' like these? Well, you have posted great problems in Level 4 & Level 5 challenge sets. The weekly challenge set (of $24{th}$ March) was also a good one. Are you going to post more of these? Also when we write details & assumptions, it appears smaller in size. Please also tell me how to do that. (I am sorry if I am boring you with this!)

My Query

###### Image credit: There, and over there

Details and assumptions

Details and assumptions

- 7 years ago

Use 6 # for image credit

You can bold or italic your "details and assumptions". To do so, use * or **.

I edited your note for easy reference.

And I updated the OEIS reference, so that the link displays correctly.

Staff - 7 years ago

@Calvin Lin, Thank You! You have been a great help.

- 7 years ago

@Finn Hulse Can you add your solution to What are Bob's chances of getting a cookie? Given that it has numerous tries and no correct as yet, I feel that your phrasing isn't sufficiently clear. There are some issues like:

1) What is 00:00 recorded as? Does it satisfy the conditions?
2) What is 00:10 recorded as? Does it satisfy the conditions?
3) I (reasonably) assume that seconds are not displayed?

Staff - 7 years ago

1. There is no such thing as 00:00. Only 12:00.

2. There is no such thing as 00:10 either. Only 12:10, which does satisfy the conditions.

3. Of course not. That would make it very easy, actually.

- 7 years ago

The "Practice" section currently shows algebra only. Will the other topics appear soon?

- 7 years ago

@Sreejato Bhattacharya Nice set of geom problems.

Do me a favor, and select the topic and level as you create the problems. This helps us with the tagging and ratings :)

Staff - 7 years ago

Hi sir. Thanks!

I didn't assign my problems any ratings in case the difficulty level I select conflicts with the difficulty level the staff thinks appropriate. I've seen that all my problems (the ones I included in the set) are rated, which probably means I can't change them anymore, right? Ok I guess I'll select the difficulty level and topic the next time I share a problem. :)

Don't worry. It helps make it easier for us to decide ratings, especially if we don't have a complete solution. Thanks for helping out :)

You can only set the level when you first created the problem. I went through your problems and assigned the topic and ratings to them.

Staff - 7 years ago

- 7 years ago

I've reshared it. It used basic ideas of analysis. Consider the shape of the graph, and what it means to have a root of multiplicity.

Staff - 7 years ago

Calvin, I see the picture you've put up for the "Stingy Rancher..." problem. I think you have a great sense of humor.

- 6 years, 11 months ago

:)

I like using pictures from the US government, as I don't have to state the image credit, which simplifies things.

Staff - 6 years, 11 months ago

Well, it makes me think of militia ranchers out in Nevada or Idaho, which is why it's funny.

- 6 years, 11 months ago

@Victor Loh That is a good set of NT questions. I would suggest that instead of placing all of the notes in the set, you simply provide a link to my/Arron's set. This way, others can more easily engage with the problems that you selected.

Staff - 6 years, 10 months ago

Ok, I will do that now.

- 6 years, 10 months ago

Mr. Calvin sir, may I ask? When will the "Challenge a Friend" option return? I'm not meaning to rush you or anything, I just wanted to know. :D

- 6 years, 9 months ago

@Andrew Bai Any reason why you deleted your questions? They seem pretty interesting to me.

Staff - 6 years, 9 months ago

I kept making errors in the problem statements, and at the time I wasn't aware of the edit function. I'll repost them.

- 6 years, 9 months ago

Great thanks!! Those are lovely problems.

Staff - 6 years, 9 months ago

Suppose I've posted a problem that turns out to have a wrong "correct" answer. Rather than having to delete the question and start over, are you saying it's possible to ask the moderator to have the wrong "correct" answer changed to the actual correct answer? Provided if I myself report it and made the request?

- 6 years, 9 months ago

Yes. You can do either of the following

1) Report the question (select answer is incorrect) and say "The correct answer is X". If you are the problem creator, we will update the answer accordingly. As always, it helps to state a simple explanation.

Imgur

The answer will be updated within 48 hours (unless we disagree with the new answer).

Staff - 6 years, 9 months ago

That's great to know that now. Thanks.

- 6 years, 9 months ago

$\pi$ is an irrational number , while $\frac{22}{7}$ is a rational number. !

- 6 years, 8 months ago

Dear Calvin, a small query... is it possible in the future to have the old Brilliant problems in a separate link "Archive" for Brilliant Squared members. Presently there seems to be no organized way to access many of these interesting problems apart from a random search.

- 6 years, 8 months ago

Dear Calvin, there is a geometry problem, "Tangent Circles" Level 5 posted by Nicotinamide Dinucleotide-Phosphate based on Descartes Theorem. I am getting an answer that is marked as incorrect which i am reasonably sure is correct. There does not seem to be any way of reporting this problem since there is no link for doing so with this problem. There is only one solver of this problem who is the originator of the the problem itself. Can you please have a look at your convenience? Thanks and regards. Satyen

- 6 years, 7 months ago

Thanks. Can you email your dispute to me, and I'd take a look at it?

My email is Calvin at Brilliant.org

Staff - 6 years, 7 months ago

Thanks. I have emailed you the details as requested. Regards again. Satyen

- 6 years, 7 months ago

Same here, so I skipped it for now. Hope it gets fixed soon.

- 6 years, 7 months ago

Satyen, so you've noticed too that you can't report that particular problem either? Yeah, that's a bug for sure. I'm still waiting for an explanation for the answer to that one, I think it should have asked for $arctan\left( \sqrt { \frac { r }{ R } } \right) =y$ . Then it makes sense.

- 6 years, 7 months ago

Yes Michael lost 25 points too. Its truly amazing how it can any solvers at all! Mystery.

- 6 years, 7 months ago

How is it possible for this problem "Tangent Circles" by "Nicotinamide Dinucleotide-Phosphate" to have 4 Solvers, when the given correct answer only makes sense if the problem asks for $arctan\left( \sqrt { \frac { r }{ R } } \right) =y$ and not the way it's posted, asking for $arctan\left( \frac { r }{ R } \right) =y$? There's some kind of bug, I can't report the problem, and meanwhile I can't go look up the solutions or make a comment about solutions, so I have no idea what's going on. But the given correct answer was so curious that I've created another problem based on it, You can guess...

This is not the first time I've noticed that a problem posting an incorrect answer nonetheless getting a number of "Solvers", which only makes me scratch my head! I think we should always be able either post a solution or make a comment about solutions, even if we've blown the problem, because many times nobody gets around to posting a solution, but meanwhile the number of "Solvers" rack up.

- 6 years, 7 months ago

Thanks for reporting the bug. We are aware of it. It arises because he has a really long name and there is no space for the other buttons. We will fix it when we can. (I've noticed that if you follow him and refresh the page, that could create enough space for the report button to appear.)

I have reported the question, and @Nicotinamide Dinucleotide-Phosphate gave a reasonable reply. I've just asked him to add a solution to the problem.

Note that being a solver only means that they submitted the correct numerical answer. If the answer is wrong, they will no longer have solved the problem when the answer gets updated.

I like the idea of having a discussion board, even when there are no solutions. In the short term, I have created one for that problem, and asked those who solved it to explain. I will think about how to incorporate a discussions board into the solutions. Thanks for your feedback.

Staff - 6 years, 7 months ago

A "reasonable reply" is what I'm looking for. I spend a considerable amount of my time trying to decipher the language of problems as posed, and I'm still tryhing to figure out his understanding of this one.

- 6 years, 7 months ago

Do you like carrots?

- 6 years, 7 months ago

wat?

- 6 years, 4 months ago

Brilliant=bunny=Agnishom=carrot=sense=logic

- 6 years, 4 months ago

Only the last two make sense.

- 6 years, 4 months ago

Was must asking if he likes carrots

- 6 years, 4 months ago

Must we also ask, following the same logic, if he likes bananas?

- 6 years, 4 months ago

You want the carrots???

$\huge{BOOM!!!}$

image

...

...

Carrots

- 6 years, 4 months ago

Nope, because carrots != bananas

- 6 years, 4 months ago

@Calvin Lin This is just a suggestion :) It would be betrer to have a confirmation box whenever a person wants to reveal a solution to the problem.

- 6 years, 5 months ago

Thanks for your numerous contributions to the Brilliant Wiki.

However, please refrain from copying directly from other sources, as that is a violation of intellectual property.

We have reverted your edits that were made in the past 2 weeks. This is your final warning. If you persist, we will take further action, like deleting your account.

Calvin

Staff - 6 years, 5 months ago

Hi Calvin. I just thought I should mention that there is an error in the second example of this wiki. If we were to apply Pythagoras directly to $\Delta ABD$ we would find that

$AD = \sqrt{84^{2} - 12^{2}} = 83.138$

to $3$ decimal places, as opposed to the given answer of $80$. I think that the problem is that, with the dimensions given, we can't have both $\angle ABC$ and $\angle BDC$ be right angles. This example has been posted on the Brilliant facebook page. :(

- 6 years, 5 months ago

Thanks for the notice. As it turns out, $ADC$ is not a straight line under these conditions. :(

I have deleted the FB post, and removed the example from the wiki page. We will update it with another suitable problem, especially one with an image.

Thanks, once again!

Staff - 6 years, 5 months ago

@Calvin Lin Quoting directly from the Vieta Root Jumping brilliant wiki page,

"If $a \geq b,$ let the other root be $c=\frac{b^2-k}{a}$. We have $c < \frac {b^2} {a} \leq b.$ If $c<0,$ then $c^2-kbc+(b^2-k)\geq c^2+k+b^2-k>0,$ which contradicts $c$ being the root of the equation. If $c=0,$ then $b^2=k,$ so $k$ is a perfect square and we are done. Otherwise, we can keep going, using $(b,c)$ instead of $(a,b)$. We get a decreasing sequence of positive integers $\{a_1,a_2,a_3,...\}=\{a,b,\frac{b^2-k}{a},...\}$ so that for all $n$ the pair$(a_n,a_{n+1})$ satisfies $\frac{a_n^2+a_{n+1}^2}{a_na_{n+1}+1}=k.$ Clearly, this sequence cannot continue indefinitely, so at some point one of the numbers will become $0,$ proving that $k$ is a perfect square. $_\square$"

The fact that $(a,b)$ satisfies the equation $\implies$ $(b,c)$ also satisfies the equation seems unjustified to me. Shouldn't it be that $(c,b)$ satisfies the equation or am I missing something. Also, does Vieta jumping apply only to symmetric polynomials? Looking forward to your reply.

Regards,
Sam.

- 6 years, 4 months ago

@Calvin Lin In case my main question is indistinguishable from the quote, I write here independently.

The fact that $(a,b)$ satisfies the equation $\implies$ $(b,c)$ also satisfies the equation seems unjustified to me. Shouldn't it be that $(c,b)$ satisfies the equation or am I missing something. Also, does Vieta jumping apply only to symmetric polynomials?

- 6 years, 4 months ago

You are right in saying that " $(a,b)$ satisfies the equation $\Rightarrow (c,b)$ satisfies the equation". In this case, since the equation is symmetric, we thus get that $(b,c)$ satisfies the equation.

Vieta jumping doesn't need to apply solely to symmetric polynomials, but that is the most often use-case. For non-symmetric polynomials, we have the chain $(x,y): (a_1, b_1 ) \Rightarrow (a_2, b_1) \Rightarrow (a_2, b_2) \Rightarrow (a_3, b_2) \Rightarrow \ldots$. In this case, the distinction between x and y is made more stark, and we cannot flip them due to the lack of symmetry. It is not clear how both the symmetric and non-symmetric chains are actually the same.

Staff - 6 years, 4 months ago

@Arpit Sah This is Part 1, which happened before we decided to make a mini-series.

You could add in other "Proof without words" problems and posts by the Brilliant Community. I like @Mursalin Habib notes like Turn The Pencil Around.

Staff - 7 years, 1 month ago

@Zi Song Yeoh Oh gosh, your Trollathon problems are just cruel. I could do the first few, and then quickly got stuck.
I'm looking forward to attempting Trollathon 2 when I have time this weekend!

Staff - 7 years, 1 month ago

@Andres Badel Congrats on being the first to finish both Level 4 and Level 5 sets. Any words of encouragement for the rest?

Staff - 7 years, 1 month ago

Hey @Calvin Lin, what is that in your Tupperware container next to your laptop? Brain food?

- 7 years, 1 month ago

Nah, just Vitamin C (hence the orange hue). Came down with the flu last week, so I'm currently overdosing on it. I love chewable vitamin C, almost as good as gummy bear Vitamin C.

Staff - 7 years, 1 month ago

@Calvin Lin I was looking at your recent Amphibious Car problem, and noticed that the graphic thingamajig had no image credit. Does this mean that you created it yourself, and if so, how? I could use some visual-creation website for my projects :)

- 7 years, 1 month ago

@Jackie Steck helped me to create it. It's a great gif isn't it? She might be able to give you some advice.

Staff - 7 years, 1 month ago

Thanks, it does look good. I'll be sure to ask her if I need some gif pointers.

- 7 years, 1 month ago

@Tristan Shin Nice set on Formulas And Theorems! I'm glad I stumbled upon it.

Can you remove "Construction Time" from your set? You can do so by hovering over the item which would cause the "move" and "trash can" icons to appear, and then click the trash can. In the image below, you can see the icons in my 2th item.

Image

Staff - 7 years, 1 month ago

Thanks! I removed the faulty Construction Time problem and also added a new note about sequences.

- 7 years, 1 month ago

@Josh Rowley I actually think that dice sums 2 is harder than dice sums 3. You can apply @Rohit Singh 's insight in dice sums 1, which makes dice sums 3 pretty immediate.

Staff - 7 years, 1 month ago

It's just that's the order I thought them up in so I claimed they were getting harder, but when I tried to edit the titles (effectively reorder them) I'm not able to, I can only change the question itself. So if you could switch the labels that would be great

- 7 years, 1 month ago

Ah, I was referencing "This is the final (and hardest) of the dice sum problems."

There are a variety of techniques that can be used to approach such problems. I don't think you have brought in the ideas of generating functions or evaluating the function at roots of unity. A harder variant will be to use $n$ dice, where the $i$th dice has $2^i$ sides.

Staff - 7 years, 1 month ago

@Robert Fritz What kind of new form of stupid assessment tests? The new SAT's?

Staff - 7 years ago

Hi, @Calvin Lin, Can you look into this problem? The answer given is wrong and I don't know why it has got a rating. Also, contrary to the difficulty level of the problem, the rating given is ridiculously high. Thanks.

- 7 years ago

The best way to get our attention about issues with problems would be to submit a clarification or dispute. Prior to today (last 8 hours), only 1 dispute was submitted.

I have since fixed it, and you can look into the solution discussions for more details.

Staff - 7 years ago

Thanks.

- 7 years ago

@Finn Hulse Please do not remove the flag from a problem unless you have dealt with it.

Let me know when you have clarified the phrasing of the problem Algotihmic Snowman, and I will remove the word "(wrong)" from the title.

Staff - 7 years ago

It's already been fixed. I changed "composite" to "not prime". Is there anything else?

- 7 years ago

The phrasing of the problem wasn't clear, though your intention could be deduced. You stated:

The probability that Bob will throw Olaf is the same as the probability that a random positive integer less than 1000 is prime. If he is thrown, he has a $\frac 2 3$ chance of survival. If the number Bob selects isn't prime, Olaf will not be thrown.

I pointed out these issues:
1) At what point in time does Bob select a number? It is never stated that he does so.
2) "is same as the probability", this merely means that the probability of events are the same. It does not imply that the events are the same, i.e. it is the even that Bob picked a prime number.

I've rephrased your entire paragraph. Please check that it reflects what you are thinking.

Staff - 7 years ago

Okay great! But you took out the stuff about the individual probabilities for each case. :O

- 7 years ago

For which case? Edit the problem as you see fit.

Staff - 7 years ago

Dude, I totally forgot! :|

- 7 years ago

Ah. I see what I left out. Thanks!

Staff - 7 years ago

@Finn Hulse There are many ways of saying something. The hard part is figuring out which way speaks exactly to you (since it would also depend on what you are familiar with). The harder part is figuring out which way speaks to the widest audience.

Staff - 7 years ago

Hah, yeah. I think that's actually really cool how that works! Like, you know, how adding another odd still makes the probability depend entirely on what was there before. :O

- 7 years ago

@Calvin Lin, have the 'best of' accounts been deleted? If it would be so, I would be horrified! Anyway, would we always get rated problems under the hash-tags?

- 7 years ago

@Calvin Lin, Cantor's continuum hypothesis had already faults in it & also, Gödel had proved that any theory with axiomatic definitions would be unstable. But, in my opinion, Mathematics is a language which appeals to our reasoning. But, it is hard to find a logical foundation to mathematics. What do you think?

- 7 years ago

Hahahahaha..

- 6 years, 12 months ago

@Snehal Shekatkar, what are you laughing at?

- 6 years, 12 months ago

@Finn Hulse I believe that you want to allow letters to repeat. If so, you should include that in the problem statement, otherwise I would assume that we're not allowed to repeat the letters.

Staff - 7 years ago

The same letter can be used more than once in each sequence. I'll add that. I'll also post a solution. :D

- 7 years ago

@Calvin Lin : Are you aware that it is possible for regular members to solve b^2 practice problems by looking at other b^2 members' activities?

- 7 years ago

- 7 years ago

Thank you. We are aware of that and working to fix it.

Staff - 7 years ago

@Snehal Shekatkar @Abhijit Bendre I would be interested in reading a writeup to the general case of Where is that hen?

Staff - 6 years, 12 months ago

Sure. I will upload it soon. Thanks for interest. By the way we are working on an interesting variation of the same problem and will put it on brilliant soon.

- 6 years, 12 months ago

Sounds exciting! I look forward to it.

Staff - 6 years, 12 months ago

@Michael Diao Can you add a solution to Remainders oh remainders? Thanks.

Staff - 6 years, 12 months ago

I did just now :)

- 6 years, 12 months ago

Perfect, thanks!

Staff - 6 years, 12 months ago

Hi! I posted the following note on recurrence relations a few days ago containing a few problems am working with right now but didn't get any replies.....it will be extremely helpful if you give a few hints or reshare it for a wider audience Click here

- 6 years, 12 months ago

@Calvin Lin - Please describe your journey to the IMO. How was it? How did you prep? What suggestions would you give to a weakling like me to achieve this status. And yes, please do answer @Satvik Golechha questions. They are also good.

- 6 years, 11 months ago

- 6 years, 11 months ago

I'd want to know who is the guy in the picture?

- 6 years, 11 months ago

The answer is obvious and left as an exercise to the reader.

Staff - 6 years, 11 months ago

- 6 years, 11 months ago

@Calvin Lin, I need help! Which format is accepted? Looks like there is a fault in my PC. Try to help. Please.

why

- 6 years, 11 months ago

Hmmm, I think that's a bug with our code, I think because of how we implemented the image uploads, we decided it would be a good idea to validate the filename in javascript and then the actual file on the server once it got there. It seems like the javascript validation is not very "smart" and probably matches in a case sensitive way, as in jpg but not JPG. I will add it as something for us to look into, though it will probably be a lower priority thing. In the mean-time, you can try renaming the file from .JPG to .jpg before uploading.

Staff - 6 years, 11 months ago

We have fixed this bug, and you can upload files with formats of JPG and PNG.

Staff - 6 years, 10 months ago

Capng

- 6 years, 11 months ago

Sir, Here is my note on Stochastic Programming.It will be extremely helpful for me if you write a small review of that note I mean in the sense how I can make it better.....I put a lot of effort into this one but it didn't get attention.

- 6 years, 11 months ago

@Paul Ryan Longhas I've noticed that your 4 most recent problems have all been flagged for errors. Can you please review the disputes and update them accordingly? Otherwise I'd be deleting your questions.

Staff - 6 years, 11 months ago

@Anik Mandal In your problem Who should be the winner, I do not understand what you mean by "A bishop,threatens a square it is placed one."

Staff - 6 years, 11 months ago

I just wanted to say that the square occupied by one bishop,cannot be occupied by the other bishop.Actually those squares are sealed and they cannot be used once again in the movement of either the bishops.You have to deal with the other squares.Is that perfect?

- 6 years, 11 months ago

@Krishna Ar RE techniques trainer, check out my sets, "Olympiad Algebra" etc, or Arron's sets "Algebra Techniques" etc.

Staff - 6 years, 11 months ago

Ok! Thanks! Anyway may I know why it was taken down? What about "Olympiad Geoemtry"?

- 6 years, 11 months ago

Every once in a while I run into a nice problem, but end up being told that my answer doesn't fly. The normal recourse is to report it, and sometimes eventually the problem or the answer is changed. Wouldn't it speed things up if I'm able to forward a complete solution, so that nobody else has to duplicate the effort from scratch? This is a good case in point: Find the Distance...

- 6 years, 10 months ago

Certainly, you should feel free to include a complete solution when you are disputing the answer. You can do so by typing that in the comment box, or providing a link to an image of your solution. I generally prefer this, since it makes reviewing of the problem much easier. I would also have more confidence when updating an answer, when the author has declined to respond.

We did not make submitting a complete solution necessary, as that would instead greatly lower the reporting rate.

Staff - 6 years, 10 months ago

Are Brilliant T Shirts still available?

- 6 years, 10 months ago

@Jai Gupta , I do not see any significant edits made to this problem. The request is for you to state if the angle is in degrees or in radians.

Please check that you have received an email with regards to the clarification request. Thanks.

Staff - 6 years, 10 months ago

@Calvin Lin , thank you for reviewing the problem. That was a major screw-up on my part.

- 6 years, 10 months ago

@Calvin Lin , I've a thing to ask you! Can you give me the link from where I can find the web page: "Challenges | Brilliant". Please?

- 6 years, 10 months ago

I missed that solution 1+3+4=8. The other two 1+2+4=7 and 1+2+5=8 are impossibilities. I need to be out of town for a few days, so I had to delete the question and will repost it later.

- 6 years, 10 months ago

Thanks! Ignore the other email.

Have a safe trip.

Staff - 6 years, 10 months ago

Your point in your last email to me is good, but this hastily assembled problem needs a more careful re-write to eliminate the "1-3-4" solution. Okay, I need to go out the door now. This was originally a "proof requested" problem, but I wanted to find a way to convert this into a Brilliant format style problem. Let me think on it when I get back, and thank you very much for your timely report this morning.

- 6 years, 10 months ago

Just a quick question: Im new to Brilliant and don't know if this is supposed to happen but 1 was level 2 in geometry and was demoted to level 1.

- 6 years, 10 months ago

Hi BJ, welcome to Brilliant! How do you like it so far?

That behavior is intentional. Your level will change according to how you perform on the questions. As you get problems right, your level will increase. As you get problems wrong, your level will decrease.

Staff - 6 years, 10 months ago

It's really nice and its enjoyable.

- 6 years, 10 months ago

In your question Gloves Galore, it is not clear to me why the answer is 13. Did you mean for the answer to be 3 instead?

Staff - 6 years, 10 months ago

Not quite. It is 13 because he has 12 pairs of gloves, 24 individual ones. A pair is a right and a left handed glove, right? He has 12 right handed gloves and 12 left handed gloves. If he picked 3 gloves,he could pick out 3 right handed gloves, and a right handed glove can't go on a left hand. If he picked 13 gloves, and ended up picking 12 right handed gloves, it assures him that he will pick a left handed glove as the 13th glove, and therefore have a pair.

- 6 years, 10 months ago

Where can you find your rating in different categories? I've been looking and still can't find it.

- 6 years, 10 months ago

@Calvin Lin I liked the minor modifications done to the brilliant recently! But I want to point out two things: (1) If I add a new tag like #OlympiadMath to "My Topics" it doesn't appear in the topic list as before, so I've make a search for it again and again. Please fix it. (2) There's glitch here in grammar: When you visit a tag and point to "add to my topics", it's wrongly written as "Add to My Topics My Topics" @Finn Hulse

- 6 years, 9 months ago

@Calvin Lin What was your experience with the IMO and what training did you do to get there?

- 6 years, 9 months ago

@Calvin Lin @Finn Hulse I had recently shared a problem a day ago, but it still shows 0 posts in my stats! Please fix it!

- 6 years, 9 months ago

I'm not an admin... Sorry. :O

- 6 years, 9 months ago

- 6 years, 9 months ago

I know. But no doubt he has received your complaint. He is very mysterious in his ways... :D

- 6 years, 9 months ago

Thanks for notifying us. The number actually refers to notes, and we've updated the name accordingly.

Staff - 6 years, 9 months ago

Thanks. But would the number of problems posted also be shown? And what happened with the scratchpad?

- 6 years, 9 months ago

@Calvin Lin, I liked the new format. But does that mean that Ratings are deleted permanently?

- 6 years, 9 months ago

I know Brilliant is still working on points and ratings (Khim mentioned this a couple of weeks ago), but how is it decided which problems start out with 100 points and and which are stuck with 10 points? The "Christmas Tree Farm" is still at 10 points, even though over 100 people have looked at it with no solvers. I don't think it's a very difficult problem, but I'd like to understand better what makes posted problems stay in the netherworld of "10 point problems", so that I can better avoid designing problems that do that. My guess is that the problem has to be at least solved by some people, would that be right?

Christmas Tree Farm

Differential geometry was my favorite subject when I was in high school, so I have nostalgic memories for this kind of thing. I thought I'd share some ideas about it.

- 6 years, 9 months ago

Thanks for sharing the question. I really enjoyed thinking about it.

Questions which were given an initial level by the creator would start off at 100 points.
Questions which were not given an initial level, will stay at 10 points till its level gets activated.
Having a low percentage of solvers is often an indication that the problem is wrong, and so we're more cautious about awarding points/ratings.

Staff - 6 years, 9 months ago

I figured it might be something like that. Brilliant continues to evolve. Before, I was hesitant to give my problems a rating, because I know much it could hurt those who try to solve it should there be problems with my problems. Now that someone has finally solved "my favorite posed problem" (Christmas Tree Farm), I see that it has a rating.

I still try to figure out what kind of problems are most appropriate for Brilliant. I know plenty of problems that are horribly mean and complicated, and not fair for students that don't have fast math software and wouldn't have time for them anyway---but I try to stick to the ones "that could maybe be solved on the back of an envelope with a pencil".

- 6 years, 9 months ago

Sorry for bothering you with this, but I wasn't sure where else to ask this question. For the last couple of days the LaTeX code hasn't been converting properly for me, so all I see is a jumble of code. (It is still converting on other sites I frequent, however.) I can still "translate" most of the questions in my head, although it can be a slog sometimes, but I can't really post solutions anymore as I have no way of knowing if I have coded correctly. I can't recall doing anything on my end that would have led to this glitch. Do you have any ideas on how I can rectify this situation? Thanks in advance for your help.

Update: The LaTeX coding is converting again, so all is well. Still wondering whether the problem was with the site or my computer, since the problem seemingly just resolved itself.

- 6 years, 9 months ago

Brian, Thanks for reporting this. We've seen this happen sporadically, but haven't been able to track it down specifically. I'm glad that it has been resolved for you. Please let me know if you see it again.

8/18 Edit: We believe that we have found the reason for this to happen, and fixed it. Let me know if you see it again.

Staff - 6 years, 9 months ago

How do you know how close you are to levelling up?

- 6 years, 9 months ago

That information is currently not available.

Staff - 6 years, 9 months ago

How do you post a direct link to something?

- 6 years, 9 months ago

Using mardown code, type "[Title] (url link)" with the spaces removed.

I edited your comment to give you an example, so you can refer to it.

Staff - 6 years, 9 months ago

What would be possible if humans used 100% of their brain power?

- 6 years, 9 months ago

I don't know. I'm going to watch "Lucy" this weekend.

Staff - 6 years, 9 months ago

This is a recurring problem. When posting a problem, how do you review the "Attached Image" and adjust the size of it before it's posted? After it's posted, I'm forced to delete the problem if I want to make changes to the attached image. I have a hard time predicting how large the final image will be, given the image file I use.

- 6 years, 9 months ago

We have not provided the ability to edit images yet. Do you feel this would be useful?

If the images are too large, we resize them to a horizontal width of 500 pixels / vertical height of 250 pixels.

We resize images to fit their display into the feed. This process is slightly more complicated and we typically do not display the entire image due to size constraints.

Staff - 6 years, 9 months ago

If Brilliant problems are now being shown on smartphones, with their tiny screens (I think there's an app for that now?), I think better control over how it first appears on them would help. Especially if it's the image used for reference in solving the problem. I try to make it as readable as possible. Maybe when your staff has time, develop better tools and guidelines regarding the "start here" image. At least give Brilliant users trhe ability to swtich images once the problem is posted.

- 6 years, 9 months ago

In my problem Evildoer's Plot-Part 2 shows the answer as something that I didn't put in. Is it because ten-thousandths are too small for it or would it take that answer as well?

- 6 years, 9 months ago

I see that your answer is given as 0.00XX. It sounds like there is a missing digit? If so, please let me know what to update the answer to. You can either email me directly at Calvin at Brilliant.org, or submit a dispute to your question.

Staff - 6 years, 9 months ago

I said they have to round to the nearest ten-thousandth. Is that the problem?

- 6 years, 9 months ago

That should be fine.

I do not understand "The second archenemy has a 0 percent chance, and so on.". If it was 90 percent, that might make more sense to me. Can you clarify what the pattern is?

Staff - 6 years, 9 months ago

Is the problem better now?

- 6 years, 9 months ago

@Calvin Lin , can you please fix up the typo I created in my problem Parallelogramania? I forgot one of the 'L's in the title. I profusely hate typos. Thanks

- 6 years, 9 months ago

My set SUGAR CUBE PUZZLE still has problems that do not have a level. Can you please give them a level?

- 6 years, 9 months ago

As a heads up, Fermi estimate / Physical estimation questions tend to not be well received, and you will likely encounter a lot of disputes.

It would be best to stick to items which have a "fixed" typical dimension, instead of one that are very subjective. E.g. A living room of a 1-room apartment would be very smaller than the living room of a duplex.

Staff - 6 years, 9 months ago

Did Brilliant get updated? If so, can you please tell me the new updates?

- 6 years, 9 months ago

@Calvin Lin I've always wondered about one thing: when we report problems, can we use $\LaTeX$ and [website] (www.example.com) and bold, italic text while we type? Can you see all these elaborate writing styles?

- 6 years, 9 months ago

Not currently. We forward on the entire text in an email to the problem creator, and so it doesn't include latex or markdown conventions.

Staff - 6 years, 9 months ago

There might be a bug in reporting a problem with this one

The hardest integral ever!!

I've tried reporting the fact that the “correct answer” expression numerically works out to 0.597385197... while the definite integral works out to 0.597381809..., which means that the "answer" of "11" is misleading. It implies there is an exact mathematical expression for this definite integral. At least it's not that one, as given. But something is preventing me from reporting this problem? Can't get through.

- 6 years, 9 months ago

Overnight, we had an issue with reporting problems. We have since fixed it, and you can report problems as usual. Sorry for the inconvenience.

Note that for the calculus problem has since been rephrased.

Staff - 6 years, 9 months ago

well, I still can't report. I was about to report this one since (and additionally he also had in mind $|a_2|$, not $a_2$) $a_2$ can be negative and so the arithmetic mean has a minimum that is a negative number, but the minus sign can be either on $a$ or on $b$, which means his answer isn't unique.

- 6 years, 9 months ago

Thanks for letting me know. The (new) issue that I'm aware of, is that members using Firefox are unable to open up the "dot dot dot" menu. However, it still works for IE or Chrome members.

Would this be an accurate description of your issue? Otherwise, can you provide me with more details, like the Browser that you are using, and the series of steps that you took?

Staff - 6 years, 9 months ago

oh, wow, it's suddenly started to work. It didn't work 5 minutes ago, also didn't work a few hours ago. I use Chrome, but everything's fine now.

- 6 years, 9 months ago

@Harshvardhan Mehta There was a submitted dispute which explains why the answer was changed. Please check that you receive emails from us.

Staff - 6 years, 9 months ago

yes i got my mistake while solving the problem all over again and anyways thanks a lot for bringing it to my notice..

- 6 years, 8 months ago

Can anyone tell me what parts of Brilliant got updated? Thanks

- 6 years, 8 months ago

Brilliant is constantly undergoing updates and changes, as we improve the experience for all out members. Unless you have a specific area in mind, the question would be hard to answer.

The most recent major change to the user experience that we did, was to change the newsfeed format to have larger pictures, and be more pleasing to the eye.
In terms of content, we have also been adding more skills into the practice map. Over the past month, we've built out the SAT and ACT maps. Geometry trigonometric skills were recently developed, and we're going to further out the Calculus map over the next month.

Staff - 6 years, 8 months ago

Thanks!

- 6 years, 8 months ago

If you solve a level 3 problem but later it becomes level 5, do your points increase or stay the same?

- 6 years, 8 months ago

They stay the same. It is only affected by what happens at the point you answered the problem.

Similarly, if you solved a level 5 problem and it later becomes level 3, your points stay the same.

Staff - 6 years, 8 months ago

Thanks!

- 6 years, 8 months ago

@Yan Yau Cheng Can you check if this problem was from the JOMO, and if so, is the given answer the same as yours?

It sure is unusual that Wolfram Alpha doesn't agree with the answer, but it is correct. Wolfram Alpha doesn't mention the existing the solution $x=-1$. We have that either the base is $1$ or the base is $-1$ and the exponent is even (which both give us the solutions $1$ and $-1$) or the exponent is $0$ and the base is not $0$ (which gives us, because of the Vieta's formula, the sum $37$ and the solutions in this case don't overlap with $1$ and $-1$ and we also have $x\neq 0$). Thus our answer is $1-1+37=\boxed{37}$.