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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
[*]April 8th (Math Jam), 4:30pm PT/7:30pm ET, 2025 MATHCOUNTS State Discussion
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]
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.

Introductory: Grades 5-10

Prealgebra 1 Self-Paced

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0 replies
jlacosta
Apr 2, 2025
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
J
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Three-player money transfer game with unique winner per round
rilarfer   1
N 33 minutes ago by Lankou
Source: ASJTNic 2005
Ana, Bárbara, and Cecilia play a game with the following rules:
[list]
[*] In each round, exactly one player wins.
[*] The two losing players each give half of their current money to the winner.
[/list]
The game proceeds as follows:

[list=1]
[*] Ana wins the first round.
[*] Bárbara wins the second round.
[*] Cecilia wins the third round.
[/list]
At the end of the game, the players have the following amounts:
[list]
[*] Ana: C$35
[*] Bárbara: C$75
[*] Cecilia: C$150
[/list]
How much money did each of them have at the beginning?
1 reply
rilarfer
an hour ago
Lankou
33 minutes ago
J
H
Find all integer solutions to an exponential equation involving powers of 2 and
rilarfer   2
N 41 minutes ago by teomihai
Source: ASJTNic 2005
Find all integer pairs $(x, y)$ such that:
$$ 2^x + 3^y = 3^{y + 2} - 2^{x + 1}. $$
2 replies
rilarfer
an hour ago
teomihai
41 minutes ago
J
H
Winning strategy in a two-player subtraction game starting with 65 tokens
rilarfer   1
N an hour ago by CHESSR1DER
Source: ASJTNic 2005
Juan and Pedro play the following game:
[list]
[*] There are initially 65 tokens.
[*] The players alternate turns, starting with Juan.
[*] On each turn, a player may remove between 1 and 7 tokens.
[*] The player who removes the last token wins.
[/list]
Describe and justify a strategy that guarantees Juan a win.
1 reply
rilarfer
an hour ago
CHESSR1DER
an hour ago
J
H
Radius of circle tangent to two equal circles and a common line
rilarfer   1
N an hour ago by Lankou
Source: ASJTNic 2005
Two circles of radius 2 are tangent to each other and to a straight line. A third circle is placed so that it is tangent to both of the other circles and also tangent to the same straight line.

What is the radius of the third circle?

IMAGE
1 reply
rilarfer
an hour ago
Lankou
an hour ago
J
H
Four-variable FE mod n
TheUltimate123   2
N an hour ago by cosmicgenius
Source: PRELMO 2023/3 (http://tinyurl.com/PRELMO)
Let \(n\) be a positive integer, and let \(\mathbb Z/n\mathbb Z\) denote the integers modulo \(n\). Determine the number of functions \(f:(\mathbb Z/n\mathbb Z)^4\to\mathbb Z/n\mathbb Z\) satisfying \begin{align*} &f(a,b,c,d)+f(a+b,c,d,e)+f(a,b,c+d,e)\\ &=f(b,c,d,e)+f(a,b+c,d,e)+f(a,b,c,d+e). \end{align*}for all \(a,b,c,d,e\in\mathbb Z/n\mathbb Z\).
2 replies
TheUltimate123
Jul 11, 2023
cosmicgenius
an hour ago
J
H
Functional divisibility for large arguments
Assassino9931   3
N an hour ago by Assassino9931
Source: Bulgaria Winter Mathematical Competition 2025 12.3
Determine all functions $f: \mathbb{Z}_{\geq 2025} \to \mathbb{Z}_{>0}$ such that $mn+1$ divides $f(m)f(n) + 1$ for any integers $m,n \geq 2025$ and there exists a polynomial $P$ with integer coefficients, such that $f(n) \leq P(n)$ for all $n\geq 2025$.
3 replies
Assassino9931
Jan 27, 2025
Assassino9931
an hour ago
J
H
Max integer divisible by 25 with leftover equal to one-fourth of a share
rilarfer   0
an hour ago
Source: ASJTNic 2005
In preparation for a piñata, a certain number of candies was bought to be equally distributed among 25 guests. However, during the distribution, it was noticed that one-fourth of the amount each guest should receive was always left over.

What is the greatest number of candies that could have been originally purchased?
0 replies
rilarfer
an hour ago
0 replies
J
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Combinatorics
TUAN2k8   2
N an hour ago by soryn
A sequence of integers $a_1,a_2,...,a_k$ is call $k-balanced$ if it satisfies the following properties:
$i) a_i \neq a_j$ and $a_i+a_j \neq 0$ for all indices $i \neq j$.
$ii) \sum_{i=1}^{k} a_i=0$.
Find the smallest integer $k$ for which: Every $k-balanced$ sequence, there always exist two terms whose diffence is not less than $n$. (where $n$ is given positive integer)
2 replies
TUAN2k8
Today at 8:22 AM
soryn
an hour ago
J
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source own
Bet667   5
N 2 hours ago by GeoMorocco
Let $x,y\ge 0$ such that $2(x+y)=1+xy$ then find minimal value of $$x+\frac{1}{x}+\frac{1}{y}+y$$
5 replies
Bet667
4 hours ago
GeoMorocco
2 hours ago
J
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Cross-ratio Practice!
shanelin-sigma   3
N 2 hours ago by MENELAUSS
Source: 2024 imocsl G3 (Night 6-G)
Triangle $ABC$ has circumcircle $\Omega$ and incircle $\omega$, where $\omega$ is tangent to $BC, CA, AB$ at $D,E,F$, respectively. $T$ is an arbitrary point on $\omega$. $EF$ meets $BC$ at $K$, $AT$ meets $\Omega$ again at $P$, $PK$ meets $\Omega$ again at $S$. $X$ is a point on $\Omega$ such that $S, D, X$ are colinear. Let $Y$ be the intersection of $AX$ and $EF$, prove that $YT$ is tangent to $\omega$.

Proposed by chengbilly
3 replies
shanelin-sigma
Aug 8, 2024
MENELAUSS
2 hours ago
J
H
I need help to reset progress in a certain subject but not all subjects
dwead   3
N Today at 12:09 PM by sillysharky
is there a way to reset progress in a certain subject but only that subject so like reset progress in algebra but not in prealgeba?
3 replies
dwead
Today at 11:31 AM
sillysharky
Today at 12:09 PM
J
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Introducing myself at AoPS, and what's your magic wand?
asuth_asuth   918
N Today at 2:21 AM by Kawhi2
Hi!

I'm Andrew Sutherland. I'm the new Chief Product Officer at AoPS. As you may have read, Richard is retiring and Ben Kornell and I are working together to lead the company now. I'm leading all the software and digital stuff at AoPS. I just wanted to say hello and introduce myself! I'm really excited to be part of the special community that is AoPS.

Previously, I founded Quizlet as a 15-year-old high school student. I did Course 6 at MIT and then left to lead Quizlet full-time for a total of 14 years. I took a few years off and now I'm doing AoPS! I wrote more about all that on my blog: https://asuth.com/im-joining-aops

I have a question for all of you. If you could wave a magic wand, and change anything about AoPS, what would it be? All suggestions welcome! Thank you.
918 replies
asuth_asuth
Mar 30, 2025
Kawhi2
Today at 2:21 AM
J
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LaTeX TeXeR PDF exporting error
Bigtree   2
N Today at 2:16 AM by Bigtree
when I try to export the following document as a PDF it says “ Error compiling LaTeX. ! LaTeX Error: Unicode character   (U+202F) not set up for use with LaTeX. ... l.96 ...the even integers from $-180 \text{ to}  360$ inclusive: ! ==> Fatal error occurred, no output PDF file produced!” here’s the document https://artofproblemsolving.com/texer/ngfubjhq
2 replies
Bigtree
Yesterday at 10:47 PM
Bigtree
Today at 2:16 AM
J
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k Question
jjmmxx   2
N Yesterday at 11:19 AM by jjmmxx
"New users are not allowed to post images in the Community."
Can you tell me about this...?
2 replies
jjmmxx
Yesterday at 11:13 AM
jjmmxx
Yesterday at 11:19 AM
J
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J
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k Reaper bug
AmberTiger79   6
N Apr 1, 2025 by AmberTiger79
So, i went to the reaper page, and it is saying that i was the least person to reap, but i never reaped. Is this supposed to happen?
6 replies
AmberTiger79
Apr 1, 2025
AmberTiger79
Apr 1, 2025
J
Reaper bug
G H J
Reveal topic tags
Reaper
L
G H BBookmark kLocked kLocked NReply
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AmberTiger79
229 posts
AmberTiger79
#1 h  Apr 1, 2025, 1:40 PM
Y by
So, i went to the reaper page, and it is saying that i was the least person to reap, but i never reaped. Is this supposed to happen?
Z Y
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AmberTiger79
229 posts
AmberTiger79
#2 h  Apr 1, 2025, 1:43 PM
Y by
And even after someone has reaped, it still won't allow me to reap
Attachments:
This post has been edited 1 time. Last edited by AmberTiger79, Apr 1, 2025, 1:45 PM
Z Y
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k1glaucus
669 posts
k1glaucus
#3 h  Apr 1, 2025, 1:49 PM
Y by
maybe hard refresh or restart? i cant reproduce
Z Y
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AmberTiger79
229 posts
AmberTiger79
#4 h  Apr 1, 2025, 1:55 PM
Y by
still doesn't work
Z Y
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plum28
121 posts
plum28
#6 h  Apr 1, 2025, 4:47 PM
Y by
Maybe it's an April fools especially for you

jk maybe try forcequitting if you're on an ipad or xing out the tab or sign out sign in.
Z Y
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k1glaucus
669 posts
k1glaucus
#7 h  Apr 1, 2025, 4:50 PM
Y by
it shows the screenshot you attached whne the page is loading but not fully loaded (i can see it for a second when I refresh), but that doesnt seewm to be your problem
This post has been edited 1 time. Last edited by k1glaucus, Apr 1, 2025, 4:50 PM
Z Y
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AmberTiger79
229 posts
AmberTiger79
#8 h  Apr 1, 2025, 4:55 PM • 1 Y
Y by Major_Monogram
Major_Monogram wrote:
H.Wires31 wrote:
Are you at Rocky Point academy? their electronouniforms screw up internet sometimes

no, i am not
Z Y
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