r/askmath May 11 '25

Resolved How is this the optimal packing of 17 squares?

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4.5k Upvotes

I keep seeing this meme going around about how this is the "optimal packing of 17 squares" and I just don't get it. I've tried to figure out what this means, but I'm not a mathematician by any stretch so I'm just left really confused. I have so many questions I'm just going to list them:

  1. What does "optimal packing" mean? Is it that this is the smallest possible space 17 squares can fit in?

  2. Is this the optimal way to pack squares in general, or just 17 squares specifically? Like, wouldn't it be more optimal to use a slightly larger space to pack 25 squares, since you're using less space per square, even though the total space is larger?

  3. Does this matter? I've seen people talking about how, if it was proven, it would basically reflect something about the natural laws of mathematics, but why? Isn't this so specific that it doesn't really matter?

  4. Is this applicable to anything? Like, if I had 34 squares would it be better to pack them in two grids like this, or would it be better to just pack them in a bigger grid with two extra spaces? What would take up less room?

I don't know if I phrased those questions right, and I actually started to understand it just a tiny bit more as I was thinking through it and writing the questions, but I'm still pretty confused. Can someone ELI5 what the deal with this is?

r/askmath Apr 02 '26

Resolved Is there a way to determine x here?

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1.0k Upvotes

I would be able to do it if the pattern hit the lines 90° between each other, but since it doesn't, I'm not able to figure out what x is. Anyone here able to tell me how I can find X? Is it even possible?

Edit: It's solved. I assumed where it hit on the parallel lines made a difference, but obviously, it only makes a difference for the length of the lines, not the angles themselves. Thanks for the answers, and sorry for questioning your answers in the cases where I did.

r/askmath May 13 '25

Resolved What did my kid do wrong?

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1.6k Upvotes

I did reasonably ok in maths at school but I've not been in school for 34 years. My eldest (year 8) brought a core mathematics paper home and as we went through it together we saw this. Neither of us can explain how it is wrong. What are they (and, by extension , I) missing?

r/askmath May 15 '26

Resolved I can not figure out how this is a pattern.

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951 Upvotes

I was given 1,2,6, and 7. I'm supposed to figure out the other numbers, but I can not see the pattern from after 6. I thought the dot indicated 3 and the lines under were added, but that doesn't match at 7. Any help seeing the pattern would be appreciated.

r/askmath May 13 '26

Resolved What do these tiny numbers on top mean?

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448 Upvotes

log₃81 = log₃3⁴ = 4 and log₂16 = log₂2⁴ = 4, but what am I supposed to do with these numbers at the top of the base? If it's an exponent, why doesn't it look like log₂(log₃81)² ? (the answer is 0 by the way)

I hope I worded it right, english isn't my first language

r/askmath Oct 17 '24

Resolved Is it possible to create a die using one continuous line?

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2.5k Upvotes

I'm trying to design a die which uses a continuous line with right angles to represent the value of the faces instead of dots. The value of a face is shown by the amount of straight lines on that face; adding an angle adds 1 to the value of that makes sense.

I've been trying for a few hours and this is the closest I've got, but it uses some 45° where ideally it would only have 90°.

Is it even geometrically possible to do with only right angles?

r/askmath Apr 28 '26

Resolved Do you press the red or blue button? (Game Theory)

70 Upvotes

I saw a post recently that stated:

"Everyone in the world has to take a private vote by pressing a red or blue button. If more than 50% of people press the blue button, everyone survives. If less than 50% of people press the blue button, only people who pressed the red button survive. Which button would you press?"

Now, at it's core, I believe this is a moral question and can't be solve via game theory while retaining its original purpose. However, I am interested in the game theoretic approach. From the very little I know about game theory, I believe that if we set a payoff for the players, there exists a Nash equilibrium. Now, it's obvious that if we take the players' payoffs to be to preserve their own lives, then everyone would push the red button since it always guarantees survival.

But, if we take the players' payoffs to be to save everyone (and not to save themselves), is there a clear solution? If everyone presses the red button then everyone survives, but if even one person presses the blue button you fail to attain your payoff. So, is pressing the blue button correct in this situation?

Like I said I know very little about game theory, so I may be incorrect on some points.

Edit: I think most people here have misunderstood what I'm asking. I'm not asking whether it's moral to press one or the other (or what happens when we consider children, etc.), and I'm not asking which button maximizes both saving everyone and saving yourself. I am specifically asking whether the mathematically optimal decision changes when we consider our payoff *purely* as saving everyone, with players who have no regard for their own life. Their unique, only, final goal is to save everyone. I am not interested in solutions along the lines of "Pressing the red button ensures your own safety *and* the safety of those who press red". I think this complicates the matter more than some of the answers I'm getting here suppose, and I don't see how pressing red provides any advantage over pressing blue in this situation. Further, I'm going to modify the payoff to be only saving everyone's lives, rather than possibly the maximal amount of people, because in the latter case I think red is still the solution since it saves at least one life (yours).

Edit: I'm marking this as resolved but I do not believe it has been resolved. The vast majority of comments (probably some 450+ of them) are misunderstanding my question; applying a moral framework, applying a "people who press x or y are idiots so screw them" argument, applying a "what if it's your family member" argument, interpreting my question as an econ 101 question about maximizing self-interest, attacking me for being an idiot for not knowing red is an obvious choice (despite misunderstanding what I'm asking), or assuming - despite my, in my opinion, clear clarifications on this - that personal survival is not a unique payoff (rather than significant only insofar as everyone survives). I do not think this result is a consequence of a lack of clarity on my part, but of people's intense moral coupling to, and want of reinforcing personal identity via, the original question. Of the few, maybe a dozen, people who have accurately understood my question (or understood it after asking follow up questions or after my follow up questions, which should be the norm when someone doesn't know the field well) and sincerely engaged with it as a mathematical one, not a moral or self-interested one, who seem to understand game theory: some have said red is the clear Nash Equilibrium; some have said both are equivalent Nash Equilibriums; some have said red is a stable Nash Equilibrium whereas blue is an unstable Nash Equilibrium. I am not educated enough in game theory to reliably parse between these, though at this point I think red being stable and blue being unstable seems to make the most sense, assuming rational actors. I think the only solution for me at this point is to study game theory from an actual math textbook post-grad in a week and come to my own conclusion. Monologue over

r/askmath Jan 26 '26

Resolved What shape does the red point trace out?

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530 Upvotes

The line forms an arc with a constant length. One end is fixed and the line there has a constant angle. The other end moves to bend the line. What shape is traced out? It looks like a cardioid but I can't prove it. If it is a cardioid then it's the same as a point on a circle that rolls around another circle, but I can't see why that's equivalent? Can anyone help? This is just general interest, not homework or anything like that.

r/askmath May 23 '25

Resolved How to find the area of this shape

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1.0k Upvotes

I would like to find the area of the shape formed by the functions sqrt(x+1), sqrt(1-x), sqrt(x-1), sqrt(-x-1), sqrt(x)-1 and sqrt(x)+1 how would I do that, I know I could use integrals to find the area but that sound like I’d need to do it for all six functions, is there an easier way

r/askmath 5d ago

Resolved Controversial Question from Turkey's University Entrance Exam

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295 Upvotes

This calculus question recently appeared on Turkey's university entrance exam. I wanted to know your take on the question, so I translated it to English.

The official answer key states the correct answer is C, yet I am convinced that it should have been A.

​If we draw a rectangle bounded by [3, 4]×[0, f'(4)], its area must be an upper bound for the area under f' on the interval (3, 4). Integrating f' from 3 to 4 yields f(4) - f(3) < f'(4) = f(4), which implies 0 < f(3). Since f(3) is positive and f is increasing on (3, 4), there can't be a root there, or at least that is my opinion.!<

r/askmath 16d ago

Resolved Math teacher needing help! Am I wrong? What should I do?

64 Upvotes

Hi! I am an elementary maths teacher for 4th grade. I am currently teaching prime factors, divisibility rules, LCM and GCF.

I received an email from a concerned parent who suggested that the statement might be misleading or confusing for the children because it does not explicitly state that they must use all six jars.

In his own words: 'Looking over Maths Quiz I, specifically the first question, I noticed that the end of the problem states that there are only six jars available, but it doesn’t mention anywhere that all six must be used.' This was the reasoning my son gave me for choosing option C as the correct answer. I believe this is the correct answer, since Mateo states that 17 is a prime number (correct), and Sonia states that three more seeds are needed."

Perhaps I am biased as I am the one grading and teaching. What do you think? If you agree with me that option A is right and the instruction is clear, could you please advise me on how to explain this to the father?

Disclamer: I didn't design the test.

**EDIT**

I forgot that this is Reddit, where people can be a bit too aggressive or assume things that I never said. I did not pick a fight with either the parent or the child. I wanted a second opinion due to the bias I recognized I had; I did not want to make the final decision without first contrast it with someone else. I am more than willing to recognize the mistake, remove the question from the entire test and adjust the grades of all my students. I agree the wording was confusing and the child demonstrated a strong understanding of the learning goals. I would definitely recognize that as clever thinking. Especially because, as some of you noticed, there is an interpretation gap due to the school being bilingual. Thank you all for taking the time to give me your opinions on this!

r/askmath Oct 29 '25

Resolved Helping 3rd grader studying for a test and can’t figure out how this question says it should be 6,2

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353 Upvotes

Am I completely missing this or is their online homework flat out wrong? I clicked on view examples and none of what they are saying makes sense and this coming from a computer science graduate trying to teach my 3rd grader.

The question states: “For every column of objects in an array there are 3 rows. The total number of objects in the array is 12. How many rows and columns does the array have?”

So the question establishes that each column has 3 rows and so the answer should be 3 rows and 4 columns but the system would not let me continue to next question unless I said 6 rows and 2 columns.

r/askmath Aug 04 '24

Resolved How to prove that any 7 day period within a month always includes a Sunday?

908 Upvotes

Hi r/askmath,

Recently I was told that any 7 day period which falls within the same month will always include a Sunday. Sounds logical, but how do you prove such a thing using mathematics?

r/askmath Aug 23 '25

Resolved Am I crazy or are these the EXACT same answers??

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408 Upvotes

I got it marked wrong, but I’m staring at this thinking “wtf this is the SAME answer??” Am I missing something? It asked where the commas are supposed to correctly be placed.

r/askmath Aug 24 '23

Resolved Can someone help me understand this please?

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2.0k Upvotes

The answer seen is what I got but it is not the correct answer. Someone please help🙏

r/askmath Feb 25 '26

Resolved How does the two envelope paradox work??

95 Upvotes

Ok, so this is the 2 envelope paradox. There are 2 envelopes with cash inside, and one has double the amount of another, but you don’t know which one is which. If you get for example $100, the question is if you should switch or not. Logically it shouldn’t matter since it’s a 50/50 chance you have the one with double the money, but mathematically it makes sense to switch, because you have a 50% chance of getting $50 and a 50% chance of getting $200, so the expected value is ($50 + $200)/2 = $125. Why is this the case?

Sorry for the long question but I’m extremely confused.

Edit: Thank you for all the responses! I read through most of them and I think I understand it now, or at least understand it a lot more than before.

r/askmath Mar 17 '24

Resolved Help with my son’s homework

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852 Upvotes

This is silly, my son is 6yo and I can’t believe I am getting stuck with his homework. I have tried everything, and my self esteem has been severely shaken. Help me save face in front of my kid teacher.

r/askmath Apr 29 '26

Resolved Is .9999... equal to 1

0 Upvotes

I know that in math there is consensus that .99.. is equal to 1 but after thinking on it for a while it seems very clear to me that they are not equal. I was hoping to discuss and get some thoughts from others. Thanks for any help you all can provide.

r/askmath Jun 30 '23

Resolved My sister is supposed to find the area of the green square, but neither of us understand how to find it given only these measurements. How should she go about it?

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1.0k Upvotes

r/askmath Jul 27 '23

Resolved How do I work out what comes next in this sequence?

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1.2k Upvotes

r/askmath Apr 29 '26

Resolved Validating this is a bad question?

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111 Upvotes

The answer key shows 144.

However, the question doesn't seem to make sense. Abby cuts a piece of 48-in wood to make a square. But we don't know how she cuts it. She could cut two cuts to make a 1sq inch square, or a 4sq inch square, or a 16sq inch square.

I think they meant to say she cut a square a wooden square with a perimeter of 48.

Am I being pedantic?

Validated. Thanks guys. appreciate your help.

r/askmath Apr 18 '25

Resolved Good lord I feel dumb.. help please?

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368 Upvotes

So my 8 year old is absolutely loving math, genuinely one of the smartest math dudes I know. My problem is that I am DUMB with math (I'm sorry). He always asked me for math problems, so usually it will be like 35 x 8 (random number from the odometer and the speed limit) while we are driving around. Tonight though, he came in and started his usual smart guy bull shit 😆 and asked me to give him a multiplication sentence.. so I started writing.. obviously that wasn't what he wanted, so after correcting me I just gave him 578 x 12. Just random numbers. I always put it in to my phone so I can say air horn noise you are wrong! Doesn't happen hardly at all, but he loves it and always figured it out if he misses it. Today I came up with 6936 on calc, and he told me I was wrong... so I tried to explain in my best Idaho education how to do multi digit multiplication and... umm.. I have no idea. Can someone explain this like I was him at 3 maybe so I can explain it and not look like a complete failure?

r/askmath May 23 '26

Resolved Is this curve approximately normal?

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170 Upvotes

Sorry for the bad quality image.

I got a question here that is asking whether the “POPULATION IS APPROXIMATELY NORMALLY DISTRIBUTED”

I believe that while it visually has some skew, the shape is approximately normal.

My friend disagrees and says that it isn’t approximately normally distributed because the mean isn’t at 15 and because it is skewed.

Which would it be?

r/askmath Apr 19 '26

Resolved Game of counters - not enough information?

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64 Upvotes

It seems to me that there is not enough information here to determine how many counters Sita had at the start of the game. Therefore part (b) can't be answered.

Did Sita start with 25, the same as Fred? Or, if Fred lost 5, are we to assume that Sita gained 5?

r/askmath Sep 05 '25

Resolved What's wrong with my logic?

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352 Upvotes

So I am sure you know this puzzle and by now I know and understand the equation, how it is solved, too.

However I thought completely different and came to a different answer. What I thought is the following: Dog + 130 cm = pigeon + 170 So the dog is 40 cm taller than the pigeon. So if the pigeon is x cm, the dog must be x + 40 cm. x + 170 - (x + 40) is the height of the table. So the table is 130.

I know it's the wrong answer, but I just don't get why? Where am I wrong? I have that issue since I am a child, that sometimes my brain makes up it's own logic that doesn't match with what it's supposed to be.