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k a May Highlights and 2025 AoPS Online Class Information
jlacosta   0
May 1, 2025
May is an exciting month! National MATHCOUNTS is the second week of May in Washington D.C. and our Founder, Richard Rusczyk will be presenting a seminar, Preparing Strong Math Students for College and Careers, on May 11th.

Are you interested in working towards MATHCOUNTS and don’t know where to start? We have you covered! If you have taken Prealgebra, then you are ready for MATHCOUNTS/AMC 8 Basics. Already aiming for State or National MATHCOUNTS and harder AMC 8 problems? Then our MATHCOUNTS/AMC 8 Advanced course is for you.

Summer camps are starting next 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 an enriching 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)!

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[*]May 21st, 4:00pm PT/7:00pm ET, Mathcamp 2025 Qualifying Quiz Part 2 Math Jam, Problems 5 and 6, Canada/USA Mathcamp staff will discuss solutions to Problems 5 and 6 of the 2025 Mathcamp Qualifying Quiz![/list]
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0 replies
jlacosta
May 1, 2025
0 replies
k i Suggestion Form
jwelsh   0
May 6, 2021
Hello!

Given the number of suggestions we’ve been receiving, we’re transitioning to a suggestion form. If you have a suggestion for the AoPS website, please submit the Google Form:
Suggestion Form

To keep all new suggestions together, any new suggestion threads posted will be deleted.

Please remember that if you find a bug outside of FTW! (after refreshing to make sure it’s not a glitch), make sure you’re following the How to write a bug report instructions and using the proper format to report the bug.

Please check the FTW! thread for bugs and post any new ones in the For the Win! and Other Games Support Forum.
0 replies
jwelsh
May 6, 2021
0 replies
k i Read me first / How to write a bug report
slester   3
N May 4, 2019 by LauraZed
Greetings, AoPS users!

If you're reading this post, that means you've come across some kind of bug, error, or misbehavior, which nobody likes! To help us developers solve the problem as quickly as possible, we need enough information to understand what happened. Following these guidelines will help us squash those bugs more effectively.

Before submitting a bug report, please confirm the issue exists in other browsers or other computers if you have access to them.

For a list of many common questions and issues, please see our user created FAQ, Community FAQ, or For the Win! FAQ.

What is a bug?
A bug is a misbehavior that is reproducible. If a refresh makes it go away 100% of the time, then it isn't a bug, but rather a glitch. That's when your browser has some strange file cached, or for some reason doesn't render the page like it should. Please don't report glitches, since we generally cannot fix them. A glitch that happens more than a few times, though, could be an intermittent bug.

If something is wrong in the wiki, you can change it! The AoPS Wiki is user-editable, and it may be defaced from time to time. You can revert these changes yourself, but if you notice a particular user defacing the wiki, please let an admin know.

The subject
The subject line should explain as clearly as possible what went wrong.

Bad: Forum doesn't work
Good: Switching between threads quickly shows blank page.

The report
Use this format to report bugs. Be as specific as possible. If you don't know the answer exactly, give us as much information as you know. Attaching a screenshot is helpful if you can take one.

Summary of the problem:
Page URL:
Steps to reproduce:
1.
2.
3.
...
Expected behavior:
Frequency:
Operating system(s):
Browser(s), including version:
Additional information:


If your computer or tablet is school issued, please indicate this under Additional information.

Example
Summary of the problem: When I click back and forth between two threads in the site support section, the content of the threads no longer show up. (See attached screenshot.)
Page URL: http://artofproblemsolving.com/community/c10_site_support
Steps to reproduce:
1. Go to the Site Support forum.
2. Click on any thread.
3. Click quickly on a different thread.
Expected behavior: To see the second thread.
Frequency: Every time
Operating system: Mac OS X
Browser: Chrome and Firefox
Additional information: Only happens in the Site Support forum. My tablet is school issued, but I have the problem at both school and home.

How to take a screenshot
Mac OS X: If you type ⌘+Shift+4, you'll get a "crosshairs" that lets you take a custom screenshot size. Just click and drag to select the area you want to take a picture of. If you type ⌘+Shift+4+space, you can take a screenshot of a specific window. All screenshots will show up on your desktop.

Windows: Hit the Windows logo key+PrtScn, and a screenshot of your entire screen. Alternatively, you can hit Alt+PrtScn to take a screenshot of the currently selected window. All screenshots are saved to the Pictures → Screenshots folder.

Advanced
If you're a bit more comfortable with how browsers work, you can also show us what happens in the JavaScript console.

In Chrome, type CTRL+Shift+J (Windows, Linux) or ⌘+Option+J (Mac).
In Firefox, type CTRL+Shift+K (Windows, Linux) or ⌘+Option+K (Mac).
In Internet Explorer, it's the F12 key.
In Safari, first enable the Develop menu: Preferences → Advanced, click "Show Develop menu in menu bar." Then either go to Develop → Show Error console or type Option+⌘+C.

It'll look something like this:
IMAGE
3 replies
slester
Apr 9, 2015
LauraZed
May 4, 2019
k i Community Safety
dcouchman   0
Jan 18, 2018
If you find content on the AoPS Community that makes you concerned for a user's health or safety, please alert AoPS Administrators using the report button (Z) or by emailing sheriff@aops.com . You should provide a description of the content and a link in your message. If it's an emergency, call 911 or whatever the local emergency services are in your country.

Please also use those steps to alert us if bullying behavior is being directed at you or another user. Content that is "unlawful, harmful, threatening, abusive, harassing, tortuous, defamatory, vulgar, obscene, libelous, invasive of another's privacy, hateful, or racially, ethnically or otherwise objectionable" (AoPS Terms of Service 5.d) or that otherwise bullies people is not tolerated on AoPS, and accounts that post such content may be terminated or suspended.
0 replies
dcouchman
Jan 18, 2018
0 replies
F.E....can you solve it?
Jackson0423   2
N a few seconds ago by InftyByond
Find all functions \( f : \mathbb{R} \to \mathbb{R} \) such that
\[
f\left(\frac{x^2 - f(x)}{f(x) - 1}\right) = x
\]for all real numbers \( x \) satisfying \( f(x) \neq 1 \).
2 replies
Jackson0423
2 hours ago
InftyByond
a few seconds ago
IMO Genre Predictions
ohiorizzler1434   44
N 5 minutes ago by Jackson0423
Everybody, with IMO upcoming, what are you predictions for the problem genres?


Personally I predict: predict
44 replies
ohiorizzler1434
May 3, 2025
Jackson0423
5 minutes ago
Number theory
MathsII-enjoy   0
18 minutes ago
Prove that when $x^p+y^p$ | $(p^2-1)^n$ with $x,y$ are positive integers and $p$ is prime ($p>3$), we get: $x=y$
0 replies
MathsII-enjoy
18 minutes ago
0 replies
CooL geo
Pomegranat   1
N 26 minutes ago by Pomegranat
Source: Idk

In triangle \( ABC \), \( D \) is the midpoint of \( BC \). \( E \) is an arbitrary point on \( AC \). Let \( S \) be the intersection of \( AD \) and \( BE \). The line \( CS \) intersects with the circumcircle of \( ACD \), for the second time at \( K \). \( P \) is the circumcenter of triangle \( ABE \). Prove that \( PK \perp CK \).
1 reply
Pomegranat
Today at 5:57 AM
Pomegranat
26 minutes ago
Reply box disappearing
Craftybutterfly   23
N Today at 4:24 AM by Craftybutterfly
For some reason, on my iPhone XR, when I press on the view my posts button, then press on an unlocked topic and scroll down or press go down button, the reply box disappears. I can’t use the proper format right now as I am on phone.
Summary of the problem: the lines above
setps to reproduce:
1. Go to your profile
2. Press on your posts button
3. press an unlocked topic and scroll down
Frequency: 100%
Browser: Chrome latest version
Device: iPhone XR
23 replies
Craftybutterfly
Apr 30, 2025
Craftybutterfly
Today at 4:24 AM
Aops is malware
Speedysolver1   29
N Today at 1:44 AM by ohiorizzler1434
See the image they are trying to track me
29 replies
Speedysolver1
May 2, 2025
ohiorizzler1434
Today at 1:44 AM
May the 4th (Late lol)
AbhayAttarde01   4
N Today at 12:26 AM by PikaPika999
nobody said this yet in site support????
Happy May 4th!
may the 4th be with you
and me my ap exams are tomorrow please be real
4 replies
AbhayAttarde01
Yesterday at 11:38 PM
PikaPika999
Today at 12:26 AM
question
JohannIsBach   2
N Yesterday at 10:42 PM by bpan2021
i have a question. where can u find what are hte most active forums?
2 replies
JohannIsBach
Yesterday at 10:33 PM
bpan2021
Yesterday at 10:42 PM
*RESOLVED* This has been going on for a while now, can anyone else relate?
jmr2010   3
N Saturday at 9:37 PM by jmr2010
Most of the time when I type in something for the tags or search for a user, the AoPS suggestion box pops up, and most of the time, when I click the suggestion, the box just disappears, meaning the automatic system usually never works
3 replies
jmr2010
Apr 29, 2025
jmr2010
Saturday at 9:37 PM
Cannot post PHP
char0221   4
N May 2, 2025 by k1glaucus
Summary of the problem: If I try to post anything with PHP (a coding language), it
Page URL: In any forum or private messages
Steps to reproduce:
1. Create a post.
2. Put some PHP inside, can't give example
Expected behavior: Should post the message
Frequency: 100%
Operating system(s): macOS Sequoia 15.2.1
Browser(s), including version: Safari
Additional information: See attachments
4 replies
char0221
Apr 30, 2025
k1glaucus
May 2, 2025
k Side Panel UI Glitch
MathPerson12321   3
N May 1, 2025 by Demetri
Ill add more detail soon but on the side panel with the global feed, my feeds, private messages, and bookmarked threads/forums, the 2nd and 4th one I just mentioned are glitched. The 2nd one has the settings icon and then a music icon, and the 4th has an aops mini cube, the share button, and another that I don't know what it is.
Private messages are also being weird as the right panel with the edit button for example is offset.
3 replies
MathPerson12321
May 1, 2025
Demetri
May 1, 2025
k How to delete a private forum you created
Platinum_Dragon   2
N Apr 30, 2025 by jlacosta
Is this possible? thank you
2 replies
Platinum_Dragon
Apr 30, 2025
jlacosta
Apr 30, 2025
k How to remove tags from a PM after you've removed yourself from it
Platinum_Dragon   2
N Apr 29, 2025 by Platinum_Dragon
Is it possible? Because it's kind of annoying to have a whole bunch of tags that stick around forever.

thank you
2 replies
Platinum_Dragon
Apr 29, 2025
Platinum_Dragon
Apr 29, 2025
k Reaper....
Happycat2   22
N Apr 29, 2025 by jlacosta
Can someone explain what the reaper is this time? I'm sorry but I don't know what "Rapper ear error a pear perrier ear ape ea games" means.
22 replies
Happycat2
Apr 27, 2025
jlacosta
Apr 29, 2025
Transforming a grid to another
Severus   3
N Apr 20, 2025 by Project_Donkey_into_M4
Source: STEMS 2021 Cat B P5
Sheldon was really annoying Leonard. So to keep him quiet, Leonard decided to do something. He gave Sheldon the following grid

$\begin{tabular}{|c|c|c|c|c|c|}
\hline
1 & 1 & 1 & 1 & 1 & 0\\ 
\hline
1 & 1 & 1 & 1 & 0 & 0\\ 
\hline
1 & 1 & 1 & 0 & 0 & 0\\ 
\hline
1 & 1 & 0 & 0 & 0 & 1\\ 
\hline
1 & 0 & 0 & 0 & 1 & 0\\
\hline
0 & 0 & 0 & 1 & 0 & 0\\
\hline
\end{tabular}$

and asked him to transform it to the new grid below

$\begin{tabular}{|c|c|c|c|c|c|}
\hline
1 & 2 & 18 &24 &28 &30\\
\hline
21 & 3 & 4 &16 &22 &26\\
\hline
23 &19 & 5 & 6 &14 &20\\
\hline
32 &25 &17 & 7 & 8 &12\\
\hline
33 &34 &27 &15 & 9 &10\\
\hline
35 &31 &36 &29 &13 &11\\
\hline
\end{tabular}$

by only applying the following algorithm:

$\bullet$ At each step, Sheldon must choose either two rows or two columns.

$\bullet$ For two columns $c_1, c_2$, if $a,b$ are entries in $c_1, c_2$ respectively, then we say that $a$ and $b$ are corresponding if they belong to the same row. Similarly we define corresponding entries of two rows. So for Sheldon's choice, if two corresponding entries have the same parity, he should do nothing to them, but if they have different parities, he should add 1 to both of them.

Leonard hoped this would keep Sheldon occupied for some time, but Sheldon immediately said, "But this is impossible!". Was Sheldon right? Justify.
3 replies
Severus
Jan 24, 2021
Project_Donkey_into_M4
Apr 20, 2025
Transforming a grid to another
G H J
G H BBookmark kLocked kLocked NReply
Source: STEMS 2021 Cat B P5
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Severus
742 posts
#1 • 2 Y
Y by ImSh95, Mango247
Sheldon was really annoying Leonard. So to keep him quiet, Leonard decided to do something. He gave Sheldon the following grid

$\begin{tabular}{|c|c|c|c|c|c|}
\hline
1 & 1 & 1 & 1 & 1 & 0\\ 
\hline
1 & 1 & 1 & 1 & 0 & 0\\ 
\hline
1 & 1 & 1 & 0 & 0 & 0\\ 
\hline
1 & 1 & 0 & 0 & 0 & 1\\ 
\hline
1 & 0 & 0 & 0 & 1 & 0\\
\hline
0 & 0 & 0 & 1 & 0 & 0\\
\hline
\end{tabular}$

and asked him to transform it to the new grid below

$\begin{tabular}{|c|c|c|c|c|c|}
\hline
1 & 2 & 18 &24 &28 &30\\
\hline
21 & 3 & 4 &16 &22 &26\\
\hline
23 &19 & 5 & 6 &14 &20\\
\hline
32 &25 &17 & 7 & 8 &12\\
\hline
33 &34 &27 &15 & 9 &10\\
\hline
35 &31 &36 &29 &13 &11\\
\hline
\end{tabular}$

by only applying the following algorithm:

$\bullet$ At each step, Sheldon must choose either two rows or two columns.

$\bullet$ For two columns $c_1, c_2$, if $a,b$ are entries in $c_1, c_2$ respectively, then we say that $a$ and $b$ are corresponding if they belong to the same row. Similarly we define corresponding entries of two rows. So for Sheldon's choice, if two corresponding entries have the same parity, he should do nothing to them, but if they have different parities, he should add 1 to both of them.

Leonard hoped this would keep Sheldon occupied for some time, but Sheldon immediately said, "But this is impossible!". Was Sheldon right? Justify.
This post has been edited 2 times. Last edited by Severus, Jan 24, 2021, 10:15 PM
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kapilpavase
595 posts
#2 • 2 Y
Y by Severus, Rg230403
Proposed by Writika Sarkar


Official Solution:
Sheldon was indeed right (of course, because he is so smart)!

For notational convenience, let $c_{ij}$ denote the entry of the grid on the $i$th row and $j$th column.

Note that whenever we perform the algorithm on two rows (or columns), we swap the parities of two corresponding entries if they were different modulo 2. This means, that if we interpret all the values modulo 2, then the algorithm switches two rows (or columns). For example, if two rows $(1,1,1,1,1,0)$ and $(1,1,0,0,0,1)$ were chosen then the algorithm transforms them to $(1,1,2,2,2,1)$ and $(1,1,1,1,1,2)$. But modulo 2, they simply get transformed to $(1,1,0,0,0,1)$ and $(1,1,1,1,1,0)$ (they are simply exchanged). Now, we associate with the $n$th step of the algorithm, a $6\times 6$ matrix $A^n$ such that $A^n_{ij}=c_{ij}$, where $A^n_{ij}$ is the entry on the $i$th row and $j$th column of $A^n$. (Here, $n=1$ corresponds to the original grid.)
Then notice the value $\det(A^n)\pmod 2$ is an invariant for all $n$, under this algorithm, since for any square matrix, switching two rows doesn't change the absolute value of the determinant. We can easily figure out that $\det(A^1)=0\equiv 0\pmod 2$, and writing the matrix for our target grid, by replacing all the entries with their values modulo 2, we can see that the determinant is $1\pmod 2$. Hence, the transformation is impossible.
This post has been edited 2 times. Last edited by kapilpavase, Jan 25, 2021, 9:08 AM
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Severus
742 posts
#3
Y by
Here's an elementary solution that doesn't involve matrices/determinants

Once we figure out that the algorithm simply switches rows/columns modulo 2, and interpret all the values in the second grid in mod 2, we can note that a row-switching only permutes the elements in the columns, but doesn't change the elements. Similarly a column-switching only permutes the elements in each row, but doesn't change the elements. Now in the first grid, the first row $(1,1,1,1,1,0)$ is the only row with five $1$s and in the second grid, the last row $(1,1,0,1,1,1)$ modulo 2, is the only row with five $1$s. This means that the first row must have shifted to the last row after some number of row-switchings. Similarly, there's only one column with exactly five $0$s in each grid, and we see that it is the last column in both the grids. However in the first grid, the intersection entry of the last column and the first row is $0$, and in the second grid, the intersection entry of the last row and last column is $1$. But for a fixed pair of row and column, row/column-switching can never change the entry in their intersection, so it's impossible to transform the first grid to the second one.
This post has been edited 1 time. Last edited by Severus, Jan 26, 2021, 6:10 PM
Reason: blah blah
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Project_Donkey_into_M4
148 posts
#5
Y by
Here are $2$ solutions by me, Distorteddragon1o4 and Sammy27

Solution 1
We work modulo $2$

Note that the operations when done row-wise ,switches the rows and same goes for the columns.Note that switching rows doesn't affect the composition of the columns i.e, the number of $1$'s or $0$'s in the columns remain the same.Now note that the composition of the columns of the first and second matrices are the same, so we can say that column switching isn't really needed i.e. switching only rows suffices. Now consider the first row of the first matrix, it has $5,1'$s and the $6$th row of the new matrix, it also has $5,1'$s.So these two needs to be switched. But note that the first row of the first matrix is $( 1,1,1,1,1,0)$ and the last row of the next matrix is $(1,1,0,1,1,1)$.The way to get the $0$ is to swap the $3$rd and $6$th row at some point. But that changes the number of $1$ in the last row, hence sherlock is correct $\blacksquare$

Solution 2
Note that the value of the determinant (with elements modulo $2$) only changes sign under the operations.Value of the first determinant is $1$ and the second one is $0$ and hence sherlock is correct.
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