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Contests & Programs AMC and other contests, summer programs, etc.
AMC and other contests, summer programs, etc.
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Contests & Programs AMC and other contests, summer programs, etc.
AMC and other contests, summer programs, etc.
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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.

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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
JSMC texas
BossLu99   26
N a minute ago by NoSignOfTheta
who is going to JSMC texas
26 replies
BossLu99
Yesterday at 1:32 PM
NoSignOfTheta
a minute ago
Question
HopefullyMcNats2025   19
N an hour ago by MC_ADe
Is it more difficult to make MOP or make usajmo, usapho, and usabo
19 replies
HopefullyMcNats2025
Apr 7, 2025
MC_ADe
an hour ago
Circumcircle of one triangle passes from another's circumcenter.
Nuran2010   1
N an hour ago by Assassino9931
Source: Azerbaijan Al-Khwarizmi IJMO TST 2024
In a parallelogram $ABCD$,$\angle A<90^\circ$ and $AB<BC$. Interior angle bisector of $\angle BAD$ intersects $BC$ at $M$, and $DC$ at $N$.Prove that circumcircle of $BCD$ passes from circumcenter of $CMN$.
1 reply
Nuran2010
Today at 4:57 PM
Assassino9931
an hour ago
sussy baka stop intersecting in my lattice points
Spectator   23
N an hour ago by MC_ADe
Source: 2022 AMC 10A #25
Let $R$, $S$, and $T$ be squares that have vertices at lattice points (i.e., points whose coordinates are both integers) in the coordinate plane, together with their interiors. The bottom edge of each square is on the x-axis. The left edge of $R$ and the right edge of $S$ are on the $y$-axis, and $R$ contains $\frac{9}{4}$ as many lattice points as does $S$. The top two vertices of $T$ are in $R \cup S$, and $T$ contains $\frac{1}{4}$ of the lattice points contained in $R \cup S$. See the figure (not drawn to scale).

IMAGE

The fraction of lattice points in $S$ that are in $S \cap T$ is 27 times the fraction of lattice points in $R$ that are in $R \cap T$. What is the minimum possible value of the edge length of $R$ plus the edge length of $S$ plus the edge length of $T$?

$\textbf{(A) }336\qquad\textbf{(B) }337\qquad\textbf{(C) }338\qquad\textbf{(D) }339\qquad\textbf{(E) }340$
23 replies
Spectator
Nov 11, 2022
MC_ADe
an hour ago
a_i/i sequence
pad   19
N an hour ago by ihatemath123
Source: TSTST 2021/2
Let $a_1<a_2<a_3<a_4<\cdots$ be an infinite sequence of real numbers in the interval $(0,1)$. Show that there exists a number that occurs exactly once in the sequence
\[ \frac{a_1}{1},\frac{a_2}{2},\frac{a_3}{3},\frac{a_4}{4},\ldots.\]
Merlijn Staps
19 replies
pad
Nov 8, 2021
ihatemath123
an hour ago
Find points with sames integer distances as given
nAalniaOMliO   2
N an hour ago by nAalniaOMliO
Source: Belarus TST 2024
Points $A_1, \ldots A_n$ with rational coordinates lie on a plane. It turned out that the distance between every pair of points is an integer. Prove that there exist points $B_1, \ldots ,B_n$ with integer coordinates such that $A_iA_j=B_iB_j$ for every pair $1 \leq i \leq j \leq n$
N. Sheshko, D. Zmiaikou
2 replies
nAalniaOMliO
Jul 17, 2024
nAalniaOMliO
an hour ago
Geometry tangent circles
Stefan4024   68
N an hour ago by zuat.e
Source: EGMO 2016 Day 2 Problem 4
Two circles $\omega_1$ and $\omega_2$, of equal radius intersect at different points $X_1$ and $X_2$. Consider a circle $\omega$ externally tangent to $\omega_1$ at $T_1$ and internally tangent to $\omega_2$ at point $T_2$. Prove that lines $X_1T_1$ and $X_2T_2$ intersect at a point lying on $\omega$.
68 replies
Stefan4024
Apr 13, 2016
zuat.e
an hour ago
My Unsolved Problem
MinhDucDangCHL2000   2
N 2 hours ago by hukilau17
Source: 2024 HSGS Olympiad
Let triangle $ABC$ be inscribed in the circle $(O)$. A line through point $O$ intersects $AC$ and $AB$ at points $E$ and $F$, respectively. Let $P$ be the reflection of $E$ across the midpoint of $AC$, and $Q$ be the reflection of $F$ across the midpoint of $AB$. Prove that:
a) the reflection of the orthocenter $H$ of triangle $ABC$ across line $PQ$ lies on the circle $(O)$.
b) the orthocenters of triangles $AEF$ and $HPQ$ coincide.

Im looking for a solution used complex bashing :(
2 replies
MinhDucDangCHL2000
Today at 4:53 PM
hukilau17
2 hours ago
Easy Combinatorics
MuradSafarli   2
N 2 hours ago by Sadigly
A student firstly wrote $x=3$ on the board. For each procces, the stutent deletes the number x and replaces it with either $(2x+4)$ or $(3x+8)$ or $(x^2+5x)$. Is this possible to make the number $(20^{25}+2024)$ on the board?
2 replies
MuradSafarli
5 hours ago
Sadigly
2 hours ago
System
worthawholebean   10
N 2 hours ago by daijobu
Source: AIME 2008II Problem 14
Let $ a$ and $ b$ be positive real numbers with $ a\ge b$. Let $ \rho$ be the maximum possible value of $ \frac{a}{b}$ for which the system of equations
\[ a^2+y^2=b^2+x^2=(a-x)^2+(b-y)^2\]has a solution in $ (x,y)$ satisfying $ 0\le x<a$ and $ 0\le y<b$. Then $ \rho^2$ can be expressed as a fraction $ \frac{m}{n}$, where $ m$ and $ n$ are relatively prime positive integers. Find $ m+n$.
10 replies
worthawholebean
Apr 3, 2008
daijobu
2 hours ago
4 variables with quadrilateral sides 2
mihaig   0
3 hours ago
Source: Own
Let $a,b,c,d\geq0$ satisfying
$$\frac1{a+1}+\frac1{b+1}+\frac1{c+1}+\frac1{d+1}=2.$$Prove
$$\left(a+b+c+d-2\right)^2+8\geq3\left(abc+abd+acd+bcd\right).$$
0 replies
mihaig
3 hours ago
0 replies
Number theory
MuradSafarli   1
N 3 hours ago by Sadigly
Prove that for any natural number \( n \) :

\[
1 \cdot 3 \cdot 5 \cdot \ldots \cdot (2n + 1) \mid (4n + 3)(4n + 5) \cdot \ldots \cdot (8n + 3).
\]
1 reply
MuradSafarli
4 hours ago
Sadigly
3 hours ago
D1025 : Can you do that?
Dattier   0
3 hours ago
Source: les dattes à Dattier
Let $x_{n+1}=x_n^3$ and $x_0=3$.

Can you calculate $\sum\limits_{i=1}^{2^{2025}} x_i \mod 10^{30}$?
0 replies
Dattier
3 hours ago
0 replies
Perpendicularity
April   32
N 3 hours ago by zuat.e
Source: CGMO 2007 P5
Point $D$ lies inside triangle $ABC$ such that $\angle DAC = \angle DCA = 30^{\circ}$ and $\angle DBA = 60^{\circ}$. Point $E$ is the midpoint of segment $BC$. Point $F$ lies on segment $AC$ with $AF = 2FC$. Prove that $DE \perp EF$.
32 replies
April
Dec 28, 2008
zuat.e
3 hours ago
2012 MOCK AIME released! (Geometry)
ProblemSolver1026   200
N Nov 25, 2023 by parmenides51
Source: Scores posted
All right! After a few long weeks of compiling, revising, deleting, compiling, deleting again…We finally have finished the MOCK AIME! Note that this is definitely one of the hardest AIME’s ever written, partly because of the sheer amount of geometry necessary and it is comprised of tedious work. Do not be disheartened if you cannot manage to finish all of them; I respect those who can even do one problem; it is an accomplishment. Also because of this, the USAMO process may be a bit flawed, and therefore, if the results of the mock AIME do not reflect on true results, a.k.a. being too hard, we will create a shorter, much easier, proof oriented competition, similar in many ways to USAMO.

You will have 2 weeks to complete this competition. If you are struggling to meet this deadline at the fact that you are on vacation, have math camps, or something else like that, please PM me, and we will discuss making your submission deadline longer. The deadline is from now- 6/17/12-7/1/12- July 1st, 2012. Any submissions after this date will be void, unless you have PMed me.

We are hoping that you will treat this like the real AIME, and spend 3 hours on it, but we have no way in enforcing that. Please just remember that you are competing against other AOPSers, and honor is important.
When you are finished, please PM your answers in the format below.
Ex. Subject: MOCK AIME ANSWERS USER: (USER)
Body:
1. 244(ANS)
2. 244(ANS)
3. …
4. …

All the way to 15. Note that 244 is NOT the answer, just a test charge. We recommend that even if you do not know how to do the problem, please submit an answer for every single one, even if you are just guessing. That way, you still have a 0.01% chance at getting it right. PM them to me!

Please additionally note that since this is a mock AIME, the answers will be in the format the positive integers between 1-999, inclusive. So if your answer turns out to be something different, please PM me if you think there is a mistake.
We wish you the best of luck, and hope you do your best!

This thread will be locked until the end of the testing period. Please PM me if you have any questions or concerns. I will be posting the solutions at the end of the testing period.
EDIT: This thread will NOT be locked.


A huge thanks to Diehard and 1=2 for everything. This could never have happened with them two. Even a greater thanks to Diehard for creating everything in the first place! Thanks to 1=2 especially because of (his) amazing problem skills.




Problem 1. The area of the circle can be expressed as $\frac{\pi}{n}$, for some positive integer $n$. Compute $n$.
Change to number 4: Find $EF^2$.
Number 5 is in degrees
Problem 6. Instead of "Find the ratio of the areas of these two triangles", it should say "The ratio of the areas of these two triangles can be expressed as $m+n\sqrt{p}$, where $m$ and $n$ are positive integers and $p$ is a prime. Compute $m+n+p$.
Problem 10. The area of region $R$ can be expressed as $n\pi$, for some integer $n$. Compute $n$.
#12: Take the answer mod 1000
Number 15 is integral.



Apologies for any inconviences this has caused.


I have attached the NEW AIME. This is the edited version, and I have changed all the mistakes. If you STILL think there are mistakes, PM me immediately.

Also note that I will accept new answers if you have PMed me the answers already, due to the mistakes.
200 replies
ProblemSolver1026
Jun 17, 2012
parmenides51
Nov 25, 2023
2012 MOCK AIME released! (Geometry)
G H J
Source: Scores posted
G
H
=
a