Stay ahead of learning milestones! Enroll in a class over the summer!

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k a April Highlights and 2025 AoPS Online Class Information
jlacosta   0
Apr 2, 2025
Spring is in full swing and summer is right around the corner, what are your plans? At AoPS Online our schedule has new classes starting now through July, so be sure to keep your skills sharp and be prepared for the Fall school year! Check out the schedule of upcoming classes below.

WOOT early bird pricing is in effect, don’t miss out! If you took MathWOOT Level 2 last year, no worries, it is all new problems this year! Our Worldwide Online Olympiad Training program is for high school level competitors. AoPS designed these courses to help our top students get the deep focus they need to succeed in their specific competition goals. Check out the details at this link for all our WOOT programs in math, computer science, chemistry, and physics.

Looking for summer camps in math and language arts? Be sure to check out the video-based summer camps offered at the Virtual Campus that are 2- to 4-weeks in duration. There are middle and high school competition math camps as well as Math Beasts camps that review key topics coupled with fun explorations covering areas such as graph theory (Math Beasts Camp 6), cryptography (Math Beasts Camp 7-8), and topology (Math Beasts Camp 8-9)!

Be sure to mark your calendars for the following events:
[list][*]April 3rd (Webinar), 4pm PT/7:00pm ET, Learning with AoPS: Perspectives from a Parent, Math Camp Instructor, and University Professor
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April 9th (Webinar), 4:00pm PT/7:00pm ET, Learn about Video-based Summer Camps at the Virtual Campus
[*]April 10th (Math Jam), 4:30pm PT/7:30pm ET, 2025 MathILy and MathILy-Er Math Jam: Multibackwards Numbers
[*]April 22nd (Webinar), 4:00pm PT/7:00pm ET, Competitive Programming at AoPS (USACO).[/list]
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0 replies
jlacosta
Apr 2, 2025
0 replies
k i Adding contests to the Contest Collections
dcouchman   1
N Apr 5, 2023 by v_Enhance
Want to help AoPS remain a valuable Olympiad resource? Help us add contests to AoPS's Contest Collections.

Find instructions and a list of contests to add here: https://artofproblemsolving.com/community/c40244h1064480_contests_to_add
1 reply
dcouchman
Sep 9, 2019
v_Enhance
Apr 5, 2023
k i Zero tolerance
ZetaX   49
N May 4, 2019 by NoDealsHere
Source: Use your common sense! (enough is enough)
Some users don't want to learn, some other simply ignore advises.
But please follow the following guideline:


To make it short: ALWAYS USE YOUR COMMON SENSE IF POSTING!
If you don't have common sense, don't post.


More specifically:

For new threads:


a) Good, meaningful title:
The title has to say what the problem is about in best way possible.
If that title occured already, it's definitely bad. And contest names aren't good either.
That's in fact a requirement for being able to search old problems.

Examples:
Bad titles:
- "Hard"/"Medium"/"Easy" (if you find it so cool how hard/easy it is, tell it in the post and use a title that tells us the problem)
- "Number Theory" (hey guy, guess why this forum's named that way¿ and is it the only such problem on earth¿)
- "Fibonacci" (there are millions of Fibonacci problems out there, all posted and named the same...)
- "Chinese TST 2003" (does this say anything about the problem¿)
Good titles:
- "On divisors of a³+2b³+4c³-6abc"
- "Number of solutions to x²+y²=6z²"
- "Fibonacci numbers are never squares"


b) Use search function:
Before posting a "new" problem spend at least two, better five, minutes to look if this problem was posted before. If it was, don't repost it. If you have anything important to say on topic, post it in one of the older threads.
If the thread is locked cause of this, use search function.

Update (by Amir Hossein). The best way to search for two keywords in AoPS is to input
[code]+"first keyword" +"second keyword"[/code]
so that any post containing both strings "first word" and "second form".


c) Good problem statement:
Some recent really bad post was:
[quote]$lim_{n\to 1}^{+\infty}\frac{1}{n}-lnn$[/quote]
It contains no question and no answer.
If you do this, too, you are on the best way to get your thread deleted. Write everything clearly, define where your variables come from (and define the "natural" numbers if used). Additionally read your post at least twice before submitting. After you sent it, read it again and use the Edit-Button if necessary to correct errors.


For answers to already existing threads:


d) Of any interest and with content:
Don't post things that are more trivial than completely obvious. For example, if the question is to solve $x^{3}+y^{3}=z^{3}$, do not answer with "$x=y=z=0$ is a solution" only. Either you post any kind of proof or at least something unexpected (like "$x=1337, y=481, z=42$ is the smallest solution). Someone that does not see that $x=y=z=0$ is a solution of the above without your post is completely wrong here, this is an IMO-level forum.
Similar, posting "I have solved this problem" but not posting anything else is not welcome; it even looks that you just want to show off what a genius you are.

e) Well written and checked answers:
Like c) for new threads, check your solutions at least twice for mistakes. And after sending, read it again and use the Edit-Button if necessary to correct errors.



To repeat it: ALWAYS USE YOUR COMMON SENSE IF POSTING!


Everything definitely out of range of common sense will be locked or deleted (exept for new users having less than about 42 posts, they are newbies and need/get some time to learn).

The above rules will be applied from next monday (5. march of 2007).
Feel free to discuss on this here.
49 replies
ZetaX
Feb 27, 2007
NoDealsHere
May 4, 2019
9 AMC 8 Scores
ChromeRaptor777   115
N 2 hours ago by valisaxieamc
As far as I'm certain, I think all AMC8 scores are already out. Vote above.
115 replies
ChromeRaptor777
Apr 1, 2022
valisaxieamc
2 hours ago
1234th Post!
PikaPika999   183
N 2 hours ago by valisaxieamc
I hit my 1234th post! (I think I missed it, I'm kinda late, :oops_sign:)

But here's a puzzle for you all! Try to create the numbers 1 through 25 using the numbers 1, 2, 3, and 4! You are only allowed to use addition, subtraction, multiplication, division, and parenthesis. If you're post #1, try to make 1. If you're post #2, try to make 2. If you're post #3, try to make 3, and so on. If you're a post after 25, then I guess you can try to make numbers greater than 25 but you can use factorials, square roots, and that stuff. Have fun!

1: $(4-3)\cdot(2-1)$
183 replies
PikaPika999
Apr 21, 2025
valisaxieamc
2 hours ago
Mathcounts Nationals Roommate Search
iwillregretthisnamelater   42
N 2 hours ago by nmlikesmath
Does anybody want to be my roommate at nats? Every other qualifier in my state is female. :sob:
Respond quick pls i gotta submit it in like a couple of hours.
42 replies
iwillregretthisnamelater
Mar 31, 2025
nmlikesmath
2 hours ago
Hard functional equation
Jessey   4
N 3 hours ago by jasperE3
Source: Belarus 2005
Find all functions $f:N -$> $N$ that satisfy $f(m-n+f(n)) = f(m)+f(n)$, for all $m, n$$N$.
4 replies
Jessey
Mar 11, 2020
jasperE3
3 hours ago
Vertices of a convex polygon if and only if m(S) = f(n)
orl   12
N 3 hours ago by Maximilian113
Source: IMO Shortlist 2000, C3
Let $ n \geq 4$ be a fixed positive integer. Given a set $ S = \{P_1, P_2, \ldots, P_n\}$ of $ n$ points in the plane such that no three are collinear and no four concyclic, let $ a_t,$ $ 1 \leq t \leq n,$ be the number of circles $ P_iP_jP_k$ that contain $ P_t$ in their interior, and let \[m(S)=a_1+a_2+\cdots + a_n.\]Prove that there exists a positive integer $ f(n),$ depending only on $ n,$ such that the points of $ S$ are the vertices of a convex polygon if and only if $ m(S) = f(n).$
12 replies
orl
Aug 10, 2008
Maximilian113
3 hours ago
Imo Shortlist Problem
Lopes   35
N 3 hours ago by Maximilian113
Source: IMO Shortlist 2000, Problem N4
Find all triplets of positive integers $ (a,m,n)$ such that $ a^m + 1 \mid (a + 1)^n$.
35 replies
Lopes
Feb 27, 2005
Maximilian113
3 hours ago
Inspired by Humberto_Filho
sqing   0
3 hours ago
Source: Own
Let $ a,b\geq 0 $ and $a + b \leq 2$. Prove that
$$\frac{a^2+1}{(( a+ b)^2+1)^2} \geq  \frac{1}{25} $$$$\frac{(a^2+1)(b^2+1)}{((a+b)^2+1)^2} \geq  \frac{4}{25} $$$$ \frac{a^2+1}{(( a+ 2b)^2+1)^2} \geq  \frac{1}{289} $$$$ \frac{a^2+1}{((2a+ b)^2+1)^2} \geq  \frac{5}{289} $$


0 replies
sqing
3 hours ago
0 replies
Inequalities
Scientist10   2
N 3 hours ago by arqady
If $x, y, z \in \mathbb{R}$, then prove that the following inequality holds:
\[
\sum_{\text{cyc}} \sqrt{1 + \left(x\sqrt{1 + y^2} + y\sqrt{1 + x^2}\right)^2} \geq \sum_{\text{cyc}} xy + 2\sum_{\text{cyc}} x
\]
2 replies
Scientist10
Yesterday at 6:36 PM
arqady
3 hours ago
$n$ with $2000$ divisors divides $2^n+1$ (IMO 2000)
Valentin Vornicu   65
N 3 hours ago by ray66
Source: IMO 2000, Problem 5, IMO Shortlist 2000, Problem N3
Does there exist a positive integer $ n$ such that $ n$ has exactly 2000 prime divisors and $ n$ divides $ 2^n + 1$?
65 replies
Valentin Vornicu
Oct 24, 2005
ray66
3 hours ago
Find the smallest of sum of elements
hlminh   0
3 hours ago
Let $S=\{1,2,...,2014\}$ and $X=\{a_1,a_2,...,a_{30}\}$ is a subset of $S$ such that if $a,b\in X,a+b\leq 2014$ then $a+b\in X.$ Find the smallest of $\dfrac{a_1+a_2+\cdots+a_{30}}{30}.$
0 replies
hlminh
3 hours ago
0 replies
Easy IMO 2023 NT
799786   133
N 4 hours ago by Maximilian113
Source: IMO 2023 P1
Determine all composite integers $n>1$ that satisfy the following property: if $d_1$, $d_2$, $\ldots$, $d_k$ are all the positive divisors of $n$ with $1 = d_1 < d_2 < \cdots < d_k = n$, then $d_i$ divides $d_{i+1} + d_{i+2}$ for every $1 \leq i \leq k - 2$.
133 replies
799786
Jul 8, 2023
Maximilian113
4 hours ago
Complicated FE
XAN4   2
N 4 hours ago by cazanova19921
Source: own
Find all solutions for the functional equation $f(xyz)+\sum_{cyc}f(\frac{yz}x)=f(x)\cdot f(y)\cdot f(z)$, in which $f$: $\mathbb R^+\rightarrow\mathbb R^+$
Note: the solution is actually quite obvious - $f(x)=x^n+\frac1{x^n}$, but the proof is important.
Note 2: it is likely that the result can be generalized into a more advanced questions, potentially involving more bash.
2 replies
XAN4
Yesterday at 11:53 AM
cazanova19921
4 hours ago
Cute diophantine
TestX01   0
4 hours ago
Find all sequences of four consecutive integers such that twice their product is perfect square minus nine.
0 replies
TestX01
4 hours ago
0 replies
9 Did you get into Illinois middle school math Olympiad?
Gavin_Deng   17
N 5 hours ago by Gavin_Deng
I am simply curious of who got in.
17 replies
Gavin_Deng
Apr 19, 2025
Gavin_Deng
5 hours ago
Marble Math
ilovebender   1
N Apr 15, 2025 by EthanNg6
John has 10 marbles with the colors red, green, or blue, all either transparent or translucent. He arranged them in a circle with the following conditions:

3 marbles right beside each other cannot be the same color
The marble across from any marble (assuming John makes a perfect circle) cannot be the same color
Red cannot be in between 2 blues
Blue cannot be between 2 greens
Green cannot be between two Reds

How many different ways can John organize these marbles? State "Impossible" if you think there is no solution. State "Undefined" if one rule doesn't follow another

What if John arranged them into two rows with 5 marbles each all right beside each other. What about 5 rows with 2 marbles each?

Post your answer down below

I just thought of this question right off the top of my head, and I didn't have time to do it, but I'd love to see your answers!

Edit: I just realized "What if John arranged them into two rows with 5 marbles each all right beside each other. What about 5 rows with 2 marbles each?" Is a bit confusing, what I meant was that if you arrange the marbles 2 by 5 (one on the top), the arrow points to what is across from that marble. Same with the 5 by 2, the arrows point that is across.
1 reply
ilovebender
Mar 18, 2021
EthanNg6
Apr 15, 2025
Marble Math
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G H BBookmark kLocked kLocked NReply
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ilovebender
210 posts
#1
Y by
John has 10 marbles with the colors red, green, or blue, all either transparent or translucent. He arranged them in a circle with the following conditions:

3 marbles right beside each other cannot be the same color
The marble across from any marble (assuming John makes a perfect circle) cannot be the same color
Red cannot be in between 2 blues
Blue cannot be between 2 greens
Green cannot be between two Reds

How many different ways can John organize these marbles? State "Impossible" if you think there is no solution. State "Undefined" if one rule doesn't follow another

What if John arranged them into two rows with 5 marbles each all right beside each other. What about 5 rows with 2 marbles each?

Post your answer down below

I just thought of this question right off the top of my head, and I didn't have time to do it, but I'd love to see your answers!

Edit: I just realized "What if John arranged them into two rows with 5 marbles each all right beside each other. What about 5 rows with 2 marbles each?" Is a bit confusing, what I meant was that if you arrange the marbles 2 by 5 (one on the top), the arrow points to what is across from that marble. Same with the 5 by 2, the arrows point that is across.
Attachments:
This post has been edited 1 time. Last edited by ilovebender, Mar 18, 2021, 2:56 AM
Reason: confusing
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EthanNg6
25 posts
#2
Y by
The translucent and transparent part is not needed to solve the problem
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