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k a June Highlights and 2025 AoPS Online Class Information
jlacosta   0
4 hours ago
Congratulations to all the mathletes who competed at National MATHCOUNTS! If you missed the exciting Countdown Round, you can watch the video at this link. Are you interested in training for MATHCOUNTS or AMC 10 contests? How would you like to train for these math competitions in half the time? We have accelerated sections which meet twice per week instead of once starting on July 8th (7:30pm ET). These sections fill quickly so enroll today!

[list][*]MATHCOUNTS/AMC 8 Basics
[*]MATHCOUNTS/AMC 8 Advanced
[*]AMC 10 Problem Series[/list]
For those interested in Olympiad level training in math, computer science, physics, and chemistry, be sure to enroll in our WOOT courses before August 19th to take advantage of early bird pricing!

Summer camps are starting this month at the Virtual Campus in math and language arts that are 2 - to 4 - weeks in duration. Spaces are still available - don’t miss your chance to have a transformative summer experience. 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 upcoming events:
[list][*]June 5th, Thursday, 7:30pm ET: Open Discussion with Ben Kornell and Andrew Sutherland, Art of Problem Solving's incoming CEO Ben Kornell and CPO Andrew Sutherland host an Ask Me Anything-style chat. Come ask your questions and get to know our incoming CEO & CPO!
[*]June 9th, Monday, 7:30pm ET, Game Jam: Operation Shuffle!, Come join us to play our second round of Operation Shuffle! If you enjoy number sense, logic, and a healthy dose of luck, this is the game for you. No specific math background is required; all are welcome.[/list]
Our full course list for upcoming classes is below:
All classes run 7:30pm-8:45pm ET/4:30pm - 5:45pm PT unless otherwise noted.

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0 replies
jlacosta
4 hours ago
0 replies
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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
J
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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
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PAGE NOT SCROLLING DOWN ALL THE WAY; GETS STUCK 1.5 POSTS BEFORE THREAD END
CurlyFalcon55   7
N an hour ago by CurlyFalcon55
Summary of the problem:
Whenever I push the big, top right "Reply" button– NOT THE SMALL LITTLE "QUICK REPLY" BAR ON THE BOTTOM, and reply, I can't scroll down all the way to the bottom of the thread that I just posted in. Sometimes, very rarely though, I doesn't scroll down all the way when I push the "Quick Reply" bar.


-----Page URL:
Anywhere in the "Introduction to Number Theory" forum in AoPS


-----Steps to reproduce:

1. Go to the link above.

2. Click any thread or create a new one.

3. Click the "Reply" button, not the quick reply bar.

4. Type a reply.

5. Push the "Submit" button.

6. Try to scroll down. if you’re lucky, the problem will reproduce.

-----Expected behavior:
To scroll all the way down.


-----Frequency:
Almost every time I push the big "Reply" button, sometimes (but rarely) when I push the "Quick Reply" bar.


-----Operating system(s):
macOS Sequoia 15.4.1


-----Browser(s), including version:
Chrome, (I don't know what version)


-----Additional information:
-It rarely does it in the "Quick Reply" bar.
-It almost always does it in the big "Reply" button on the top right.


-----Can anyone reproduce?
7 replies
CurlyFalcon55
Yesterday at 11:23 PM
CurlyFalcon55
an hour ago
J
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Ducks can play games now apparently
MortemEtInteritum   35
N 2 hours ago by pi271828
Source: USA TST(ST) 2020 #1
Let $a$, $b$, $c$ be fixed positive integers. There are $a+b+c$ ducks sitting in a
circle, one behind the other. Each duck picks either rock, paper, or scissors, with $a$ ducks
picking rock, $b$ ducks picking paper, and $c$ ducks picking scissors.
A move consists of an operation of one of the following three forms:

[list]
[*] If a duck picking rock sits behind a duck picking scissors, they switch places.
[*] If a duck picking paper sits behind a duck picking rock, they switch places.
[*] If a duck picking scissors sits behind a duck picking paper, they switch places.
[/list]
Determine, in terms of $a$, $b$, and $c$, the maximum number of moves which could take
place, over all possible initial configurations.
35 replies
1 viewing
MortemEtInteritum
Nov 16, 2020
pi271828
2 hours ago
J
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2017 IGO Advanced P3
bgn   18
N 2 hours ago by Circumcircle
Source: 4th Iranian Geometry Olympiad (Advanced) P3
Let $O$ be the circumcenter of triangle $ABC$. Line $CO$ intersects the altitude from $A$ at point $K$. Let $P,M$ be the midpoints of $AK$, $AC$ respectively. If $PO$ intersects $BC$ at $Y$, and the circumcircle of triangle $BCM$ meets $AB$ at $X$, prove that $BXOY$ is cyclic.

Proposed by Ali Daeinabi - Hamid Pardazi
18 replies
bgn
Sep 15, 2017
Circumcircle
2 hours ago
J
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Own made functional equation
JARP091   1
N 3 hours ago by JARP091
Source: Own (Maybe?)
\[ \text{Find all functions } f : \mathbb{R} \to \mathbb{R} \text{ such that:} \\ f(a^4 + a^2b^2 + b^4) = f\left((a^2 - f(ab) + b^2)(a^2 + f(ab) + b^2)\right) \]
1 reply
JARP091
May 31, 2025
JARP091
3 hours ago
J
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Euler line of incircle touching points /Reposted/
Eagle116   6
N 3 hours ago by pigeon123
Let $ABC$ be a triangle with incentre $I$ and circumcentre $O$. Let $D,E,F$ be the touchpoints of the incircle with $BC$, $CA$, $AB$ respectively. Prove that $OI$ is the Euler line of $\vartriangle DEF$.
6 replies
Eagle116
Apr 19, 2025
pigeon123
3 hours ago
J
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Parallel lines on a rhombus
buratinogigle   1
N 3 hours ago by Giabach298
Source: Own, Entrance Exam for Grade 10 Admission, HSGS 2025
Given the rhombus $ABCD$ with its incircle $\omega$. Let $E$ and $F$ be the points of tangency of $\omega$ with $AB$ and $AC$ respectively. On the edges $CB$ and $CD$, take points $G$ and $H$ such that $GH$ is tangent to $\omega$ at $P$. Suppose $Q$ is the intersection point of the lines $EG$ and $FH$. Prove that two lines $AP$ and $CQ$ are parallel or coincide.
1 reply
buratinogigle
5 hours ago
Giabach298
3 hours ago
J
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Orthocenter lies on circumcircle
whatshisbucket   90
N 3 hours ago by bjump
Source: 2017 ELMO #2
Let $ABC$ be a triangle with orthocenter $H,$ and let $M$ be the midpoint of $\overline{BC}.$ Suppose that $P$ and $Q$ are distinct points on the circle with diameter $\overline{AH},$ different from $A,$ such that $M$ lies on line $PQ.$ Prove that the orthocenter of $\triangle APQ$ lies on the circumcircle of $\triangle ABC.$

Proposed by Michael Ren
90 replies
whatshisbucket
Jun 26, 2017
bjump
3 hours ago
J
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Polish MO Finals 2014, Problem 4
j___d   3
N 4 hours ago by ariopro1387
Source: Polish MO Finals 2014
Denote the set of positive rational numbers by $\mathbb{Q}_{+}$. Find all functions $f: \mathbb{Q}_{+}\rightarrow \mathbb{Q}_{+}$ that satisfy
$$\underbrace{f(f(f(\dots f(f}_{n}(q))\dots )))=f(nq)$$for all integers $n\ge 1$ and rational numbers $q>0$.
3 replies
j___d
Jul 27, 2016
ariopro1387
4 hours ago
J
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S(an) greater than S(n)
ilovemath0402   1
N 4 hours ago by ilovemath0402
Source: Inspired by an old result
Find all positive integer $n$ such that $S(an)\ge S(n) \quad \forall a \in \mathbb{Z}^{+}$ ($S(n)$ is sum of digit of $n$ in base 10)
P/s: Original problem
1 reply
ilovemath0402
5 hours ago
ilovemath0402
4 hours ago
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Hagge-like circles, Jerabek hyperbola, Lemoine cubic
kosmonauten3114   0
4 hours ago
Source: My own
Let $\triangle{ABC}$ be a scalene oblique triangle with circumcenter $O$ and orthocenter $H$, and $P$ ($\neq \text{X(3), X(4)}$, $\notin \odot(ABC)$) a point in the plane.
Let $\triangle{A_1B_1C_1}$, $\triangle{A_2B_2C_2}$ be the circumcevian triangles of $O$, $P$, respectively.
Let $\triangle{P_AP_BP_C}$ be the pedal triangle of $P$ with respect to $\triangle{ABC}$.
Let $A_1'$ be the reflection in $P_A$ of $A_1$. Define $B_1'$, $C_1'$ cyclically.
Let $A_2'$ be the reflection in $P_A$ of $A_2$. Define $B_2'$, $C_2'$ cyclically.
Let $O_1$, $O_2$ be the circumcenters of $\triangle{A_1'B_1'C_1'}$, $\triangle{A_2'B_2'C_2'}$, respectively.

Prove that:
1) $P$, $O_1$, $O_2$ are collinear if and only if $P$ lies on the Jerabek hyperbola of $\triangle{ABC}$.
2) $H$, $O_1$, $O_2$ are collinear if and only if $P$ lies on the Lemoine cubic (= $\text{K009}$) of $\triangle{ABC}$.
0 replies
kosmonauten3114
4 hours ago
0 replies
J
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Incenter perpendiculars and angle congruences
math154   84
N 4 hours ago by zuat.e
Source: ELMO Shortlist 2012, G3
$ABC$ is a triangle with incenter $I$. The foot of the perpendicular from $I$ to $BC$ is $D$, and the foot of the perpendicular from $I$ to $AD$ is $P$. Prove that $\angle BPD = \angle DPC$.

Alex Zhu.
84 replies
math154
Jul 2, 2012
zuat.e
4 hours ago
J
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what??????????????????????
Iced_Coffee   10
N 6 hours ago by CurlyFalcon55
my "my topics" symbol (the little person looking button) and my "bookmarked topics" symbol keep randomly changing to different symbols!!!!!!!! What is happening? the 'my topics' one changed so it looked like it had a gear and a music note and I don't even know what the other one was. this has been happening for two or three days now is it happening to anyone else? please help! :what?:
10 replies
Iced_Coffee
Apr 11, 2025
CurlyFalcon55
6 hours ago
J
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Post Times are Wrong
CurlyFalcon55   7
N 6 hours ago by CurlyFalcon55
Summary of the problem:
Every time a new post is posted, instead of the time it was posted at, it says "in 41 minutes" or "in an hour" or something like that. I was wondering, is that normal? I happens pretty regularly, though not all the time.

Page URL: Anywhere in the "Introduction to Number Theory" forum in AoPS

Steps to reproduce:
1.Go to the link above.
2.a.Click on any thread or b.just create a new thread.
3.If a., and if someone just posted, the bug might reproduce, and if you post, the problem might reproduce.
If b., then post something, and you might be lucky to see it reproduce.

Expected behavior:
Show the time it's been posted.

Frequency:
Pretty often.

Operating system:
macOS Sequoia 15.4.1

Browsers, including version:
Chrome, (I don't know what version)

Additional information:
This is hard to catch. It just sneaks up on you.

Does anyone else have the same problem? :help:
7 replies
CurlyFalcon55
Yesterday at 10:30 PM
CurlyFalcon55
6 hours ago
J
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Hide tag workaround
char0221   13
N Today at 1:56 PM by CurlyFalcon55
Summary of the problem: When quoting a tip tag, hovering over it causes a glitch where the tip tag's inner contents are "stuck" below the quotes.
Page URL: Any community message boards.
Steps to reproduce:
1. Create a message.
2. Insert a quote.
3. Inside the quote, put a tip tag.
4. Submit/preview, then hover over the tip tag.
Expected behavior: Tip tag does not stay when mouse is removed.
Frequency: 100%
Operating system(s): macOS Sequoia
Browser(s), including version: Safari 18.4
Additional information:
IMAGE
Also, make sure that the quote+tip is last.
[quote=char0221]
Try to close me!
[/quote]
13 replies
char0221
May 26, 2025
CurlyFalcon55
Today at 1:56 PM
J
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J
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k For The Win
Aaronjudgeisgoat   2
N Apr 15, 2025 by jlacosta
I don't know if this is the right place to post this, but when will For The Win stop undergoing maintenance?
hopefully theres some big update or smth...
2 replies
Aaronjudgeisgoat
Apr 14, 2025
jlacosta
Apr 15, 2025
J
For The Win
G H J
Reveal topic tags
L
G H BBookmark kLocked kLocked NReply
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
Aaronjudgeisgoat
912 posts
Aaronjudgeisgoat
#1 h  Apr 14, 2025, 6:28 PM • 1 Y
Y by Exponent11
I don't know if this is the right place to post this, but when will For The Win stop undergoing maintenance?
hopefully theres some big update or smth...
Z Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
jlacosta
655 posts
jlacosta
#3 h  Apr 14, 2025, 11:53 PM • 1 Y
Y by Exponent11
Thanks for letting us know. Our engineering team is looking into this.
Z Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
jlacosta
655 posts
jlacosta
#4 h  Apr 15, 2025, 12:04 AM • 1 Y
Y by Exponent11
For The Win should now be back up!
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a