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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
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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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Advanced topics in Inequalities
va2010   18
N an hour ago by sqing
So a while ago, I compiled some tricks on inequalities. You are welcome to post solutions below!
18 replies
va2010
Mar 7, 2015
sqing
an hour ago
J
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two subsets with no fewer than four common elements.
micliva   39
N 2 hours ago by de-Kirschbaum
Source: All-Russian Olympiad 1996, Grade 9, First Day, Problem 4
In the Duma there are 1600 delegates, who have formed 16000 committees of 80 persons each. Prove that one can find two committees having no fewer than four common members.

A. Skopenkov
39 replies
micliva
Apr 18, 2013
de-Kirschbaum
2 hours ago
J
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3 knightlike moves is enough
sarjinius   2
N 2 hours ago by cooljoseph
Source: Philippine Mathematical Olympiad 2025 P6
An ant is on the Cartesian plane. In a single move, the ant selects a positive integer $k$, then either travels [list]
[*] $k$ units vertically (up or down) and $2k$ units horizontally (left or right); or
[*] $k$ units horizontally (left or right) and $2k$ units vertically (up or down).
[/list]
Thus, for any $k$, the ant can choose to go to one of eight possible points.
Prove that, for any integers $a$ and $b$, the ant can travel from $(0, 0)$ to $(a, b)$ using at most $3$ moves.
2 replies
sarjinius
Mar 9, 2025
cooljoseph
2 hours ago
J
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16th ibmo - uruguay 2001/q3.
carlosbr   21
N 2 hours ago by de-Kirschbaum
Source: Spanish Communities
Let $S$ be a set of $n$ elements and $S_1,\ S_2,\dots,\ S_k$ are subsets of $S$ ($k\geq2$), such that every one of them has at least $r$ elements.

Show that there exists $i$ and $j$, with $1\leq{i}<j\leq{k}$, such that the number of common elements of $S_i$ and $S_j$ is greater or equal to: $r-\frac{nk}{4(k-1)}$
21 replies
carlosbr
Apr 15, 2006
de-Kirschbaum
2 hours ago
J
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Weird Geo
Anto0110   1
N 2 hours ago by cooljoseph
In a trapezium $ABCD$, the sides $AB$ and $CD$ are parallel and the angles $\angle ABC$ and $\angle BAD$ are acute. Show that it is possible to divide the triangle $ABC$ into 4 disjoint triangle $X_1. . . , X_4$ and the triangle $ABD$ into 4 disjoint triangles $Y_1,. . . , Y_4$ such that the triangles $X_i$ and $Y_i$ are congruent for all $i$.
1 reply
Anto0110
Yesterday at 9:24 PM
cooljoseph
2 hours ago
J
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Happy Easter!!!
A_Crabby_Crab   36
N 3 hours ago by thinkcraze
Happy Easter to all on Aops!!!

I hope everyone on this awesome website will be filled with peace, joy and love this season (its 50 days long y'all so start partying and eat some jelly beans if you can).

36 replies
A_Crabby_Crab
Yesterday at 9:35 AM
thinkcraze
3 hours ago
J
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Hard FE R^+
DNCT1   5
N 3 hours ago by jasperE3
Find all functions $f:\mathbb{R^+}\to\mathbb{R^+}$ such that
$$f(3x+f(x)+y)=f(4x)+f(y)\quad\forall x,y\in\mathbb{R^+}$$
5 replies
DNCT1
Dec 30, 2020
jasperE3
3 hours ago
J
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Maximum of Incenter-triangle
mpcnotnpc   4
N 3 hours ago by mpcnotnpc
Triangle $\Delta ABC$ has side lengths $a$, $b$, and $c$. Select a point $P$ inside $\Delta ABC$, and construct the incenters of $\Delta PAB$, $\Delta PBC$, and $\Delta PAC$ and denote them as $I_A$, $I_B$, $I_C$. What is the maximum area of the triangle $\Delta I_A I_B I_C$?
4 replies
mpcnotnpc
Mar 25, 2025
mpcnotnpc
3 hours ago
J
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Something nice
KhuongTrang   26
N 4 hours ago by KhuongTrang
Source: own
Problem. Given $a,b,c$ be non-negative real numbers such that $ab+bc+ca=1.$ Prove that

$$\sqrt{a+1}+\sqrt{b+1}+\sqrt{c+1}\le 1+2\sqrt{a+b+c+abc}.$$
26 replies
KhuongTrang
Nov 1, 2023
KhuongTrang
4 hours ago
J
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Introducing myself at AoPS, and what's your magic wand?
asuth_asuth   938
N 4 hours ago by LostInBali
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.
938 replies
asuth_asuth
Mar 30, 2025
LostInBali
4 hours ago
J
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Tiling rectangle with smaller rectangles.
MarkBcc168   59
N 4 hours ago by Bonime
Source: IMO Shortlist 2017 C1
A rectangle $\mathcal{R}$ with odd integer side lengths is divided into small rectangles with integer side lengths. Prove that there is at least one among the small rectangles whose distances from the four sides of $\mathcal{R}$ are either all odd or all even.

Proposed by Jeck Lim, Singapore
59 replies
MarkBcc168
Jul 10, 2018
Bonime
4 hours ago
J
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Existence of AP of interesting integers
DVDthe1st   34
N 5 hours ago by DeathIsAwe
Source: 2018 China TST Day 1 Q2
A number $n$ is interesting if 2018 divides $d(n)$ (the number of positive divisors of $n$). Determine all positive integers $k$ such that there exists an infinite arithmetic progression with common difference $k$ whose terms are all interesting.
34 replies
DVDthe1st
Jan 2, 2018
DeathIsAwe
5 hours ago
J
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I need help to reset progress in a certain subject but not all subjects
dwead   6
N Yesterday at 3:00 AM by mdk2013
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?
6 replies
dwead
Saturday at 11:31 AM
mdk2013
Yesterday at 3:00 AM
J
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k Question
jjmmxx   2
N Apr 18, 2025 by jjmmxx
"New users are not allowed to post images in the Community."
Can you tell me about this...?
2 replies
jjmmxx
Apr 18, 2025
jjmmxx
Apr 18, 2025
J
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J
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k Mathcounts state
orangebear   2
N Apr 1, 2025 by orangebear
When will the state solutions come out and also does states have a math jam?
2 replies
orangebear
Apr 1, 2025
orangebear
Apr 1, 2025
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Mathcounts state
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Reveal topic tags
MATHCOUNTS
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orangebear
669 posts
orangebear
#1 h  Apr 1, 2025, 10:43 PM
Y by
When will the state solutions come out and also does states have a math jam?
Z Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
k1glaucus
669 posts
k1glaucus
#2 h  Apr 1, 2025, 10:46 PM
Y by
idk the answer to the first question, but there's a math jam scheduled for april 8th.
Z Y
The post below has been deleted. Click to close.
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orangebear
669 posts
orangebear
#3 h  Apr 1, 2025, 10:49 PM
Y by
K thank you :thumbup:
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