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k a April Highlights and 2025 AoPS Online Class Information

jlacosta 0

Yesterday at 3:18 PM

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

Yesterday at 3:18 PM

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

1 viewing

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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The daily problem!

Leeoz 57

N 21 minutes ago by yaxuan

Every day, I will try to post a new problem for you all to solve! If you want to post a daily problem, you can! :)

Please hide solutions and answers, hints are fine though! :)

The first problem is:
[quote=March 21st Problem]Alice flips a fair coin until she gets 2 heads in a row, or a tail and then a head. What is the probability that she stopped after 2 heads in a row? Express your answer as a common fraction.[/quote]

Past Problems!

57 replies

Leeoz

Mar 21, 2025

yaxuan

21 minutes ago

J

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FTW tournament!

evt917 10

N 33 minutes ago by jb2015007

[center]Since all FTW tournaments have dramatically failed, I'm trying a different format. Here is how it works:

1. Type \signup{your rating (type 800 for unrated)}

2. You will eventually be assigned to a game. I will be doing this. how i assign games

3. If you win, you get 2 points. However, if you win games in a row, you get more points per win. When you win $n$ games in a row, you score $n+1$ points instead of $2$ points. Nice, right? A tie equals $1$ point, and a loss is zero. A tie or a loss will break your win streak.

4. I do not know everybody's time preferences. Because so, I will announce in advance which two players will be playing, so they themselves can organize a game themselves. Remember, THE PLAYERS ARE ORGANIZING THE GAMES THEMSELVES!!! The format is up to them, but please make the time control at least 20 seconds. Please announce the results of the game here so i can update the scoreboard. Games can be unrated.

recommended format if you cannot decide

5. The tournament goes on until april 22nd! Extremely long, right? Note that you can still signup after the first games has started, but you will have a disadvantage because some people who signed up as soon as the tournament started already has points.

6. Once you are done with your game, I will pair you with another opponent. You may play against same people multiple times. You can also request a new partner if your's is inactive and doesn't want to play.

[rule]

Questions and Answers

All signups and ratings

[rule]

LIVE LEADERBOARD:

1st place:
2nd place:
3rd place

4th place:
5th place:

10 replies

evt917

2 hours ago

jb2015007

33 minutes ago

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2⁠0⁠⁠2⁠4

Technodoggo 71

N 42 minutes ago by RedChameleon

Happy New Year!
To celebrate the start of 2024, I've decided to put up a few facts about the year. I don't have many, so y'all should also

1

2

(1 and 2 are the same :sob: just distribute)

Post more cool facts here! Keep a running chain with quote boxes for facts. (I don't know if this technically qualifies as a marathon, but I hope this is allowed lol)

71 replies

Technodoggo

Jan 1, 2024

RedChameleon

42 minutes ago

J

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2025 MATHCOUNTS State Hub

SirAppel 218

N 42 minutes ago by MC_ADe

Previous Years' "Hubs": (2022) (2023) (2024)Please Read

Now that it's April and we're allowed to discuss, and no one else has made this yet ...
[list=disc]
[*] CA: 43 (45 44 43 43 43 42 42 41 41 41)
[*] NJ: 43 (45 44 44 43 39 42 40 40 39 38) *
[*] NY: 42 (43 42 42 42 41 40)
[*] TX: 42 (43 43 43 42 42 40 40 38 38 38)
[*] MA: 41 (45 43 42 41)
[*] WA: 41 (41 45 42 41 41 41 41 41 41 40) *
[*] FL: 39 (42 41 40 39 38 37 37)
[*] IN: 39 (41 40 40 39 36 35 35 35 34 34)
[*] NC: 39 (42 42 41 39)
[*] IL: 38 (41 40 39 38 38 38)
[*] OR: 38 (44 41? 38 38)
[*] PA: 38 (41 40 40 38 38 37 36 36 34 34) *
[*] MD: 37 (43 39 39 37 37 37)
[*] CT: 36 (44 39? 38 36 34 34 34 34)
[*] MI: 36 (39 41 41 36 37 37 36 36 36 36) *
[*] MN: 36 (40 36 36 36 35 35 35 34)
[*] CO: 35 (41 37 37 35 35 35 ?? 31 31 30) *
[*] GA: 35 (38 37 36 35 34 34 34 34 34 33)
[*] OH: 35 (41 37 36 35)
[*] AR: 34 (46 45 35 34 33 31 31 31 29 29)
[*] WI: 34 (40 37 37 34 35 30 28 29 29 29) *
[*] NH: 31 (42 35 33 31 30)
[*] DE: 30 (34 33 32 30 30 29 28 27 26? 24)
[*] SC: 30 (33 33 31 30)
[*] IA: 29 (33 30 31 29 29 29 29 29 29 29 29 29) *
[*] NE: 28 (34 30 28 28 27 27 26 26 25 25)
[*] SD: 22 (30 29 24 22 22 22 21 21 20 20)
[/list]
Cutoffs Unknown

* means that CDR is official in that state.

Notes

For those asking about the removal of the tiers, I'd like to quote Jason himself:
[quote=peace09]
learn from my mistakes
[/quote]

Help contribute by sharing your state's cutoffs!
As per last year's guidelines, refrain from problem discussion until their official release on the MATHCOUNTS website.

218 replies

SirAppel

Apr 1, 2025

MC_ADe

42 minutes ago

J

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Goes through fixed points

CheshireOrb 5

N 2 hours ago by HoRI_DA_GRe8

Source: Vietnam TST 2021 P5

Given a fixed circle $(O)$ and two fixed points $B, C$ on that circle, let $A$ be a moving point on $(O)$ such that $\triangle ABC$ is acute and scalene. Let $I$ be the midpoint of $BC$ and let $AD, BE, CF$ be the three heights of $\triangle ABC$ . In two rays $\overrightarrow{FA}, \overrightarrow{EA}$ , we pick respectively $M,N$ such that $FM = CE, EN = BF$ . Let $L$ be the intersection of $MN$ and $EF$ , and let $G \neq L$ be the second intersection of $(LEN)$ and $(LFM)$ .

a) Show that the circle $(MNG)$ always goes through a fixed point.

b) Let $AD$ intersects $(O)$ at $K \neq A$ . In the tangent line through $D$ of $(DKI)$ , we pick $P,Q$ such that $GP \parallel AB, GQ \parallel AC$ . Let $T$ be the center of $(GPQ)$ . Show that $GT$ always goes through a fixed point.

5 replies

CheshireOrb

Apr 2, 2021

HoRI_DA_GRe8

2 hours ago

J

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Unsolved NT, 3rd time posting

GreekIdiot 8

N 3 hours ago by ektorasmiliotis

Source: own

Solve $5^x-2^y=z^3$ where $x,y,z \in \mathbb Z$
Hint

8 replies

GreekIdiot

Mar 26, 2025

ektorasmiliotis

3 hours ago

J

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n=y^2+108

Havu 6

N 3 hours ago by ektorasmiliotis

Given the positive integer $n = y^2 + 108$ where $y \in \mathbb{N}$ .
Prove that $n$ cannot be a perfect cube of a positive integer.

6 replies

Havu

Today at 4:30 PM

ektorasmiliotis

3 hours ago

J

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Valuable subsets of segments in [1;n]

NO_SQUARES 0

3 hours ago

Source: Russian May TST to IMO 2023; group of candidates P6; group of non-candidates P8

The integer $n \geqslant 2$ is given. Let $A$ be set of all $n(n-1)/2$ segments of real line of type $[i, j]$ , where $i$ and $j$ are integers, $1\leqslant i<j\leqslant n$ . A subset $B \subset A$ is said to be valuable if the intersection of any two segments from $B$ is either empty, or is a segment of nonzero length belonging to $B$ . Find the number of valuable subsets of set $A$ .

0 replies

NO_SQUARES

3 hours ago

0 replies

J

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Fneqn or Realpoly?

Mathandski 2

N 4 hours ago by jasperE3

Source: India, not sure which year. Found in OTIS pset

Find all polynomials $P$ with real coefficients obeying
$P(x) P(x+1) = P(x^2 + x + 1)$ for all real numbers $x$ .

2 replies

Mathandski

6 hours ago

jasperE3

4 hours ago

J

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thanks u!

Ruji2018252 2

N 4 hours ago by CHESSR1DER

find all $f: \mathbb{R}\to \mathbb{R}$ and
$(x-y)[f(x)+f(y)]\leqslant f(x^2-y^2), \forall x,y \in \mathbb{R}$

2 replies

Ruji2018252

6 hours ago

CHESSR1DER

4 hours ago

J

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Functional equations

hanzo.ei 11

N 6 hours ago by GreekIdiot

Source: Greekldiot

Find all $f: \mathbb R_+ \rightarrow \mathbb R_+$ such that $f(xf(y)+f(x))=yf(x+yf(x)) \: \forall \: x,y \in \mathbb R_+$

11 replies

hanzo.ei

Mar 29, 2025

GreekIdiot

6 hours ago

J

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D1018 : Can you do that ?

Dattier 1

N 6 hours ago by Dattier

Source: les dattes à Dattier

We can find $A,B,C$ , such that $\gcd(A,B)=\gcd(C,A)=\gcd(A,2)=1$ and $\forall n \in \mathbb N^*, (C^n \times B \mod A) \mod 2=0$ .

For example :

$C=20$
$A=47650065401584409637777147310342834508082136874940478469495402430677786194142956609253842997905945723173497630499054266092849839$

$B=238877301561986449355077953728734922992395532218802882582141073061059783672634737309722816649187007910722185635031285098751698$

Can you find $A,B,C$ such that $A>3$ is prime, $C,B \in (\mathbb Z/A\mathbb Z)^*$ with $o(C)=(A-1)/2$ and $\forall n \in \mathbb N^*, (C^n \times B \mod A) \mod 2=0$ ?

1 reply

Dattier

Mar 24, 2025

Dattier

6 hours ago

J

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D1010 : How it is possible ?

Dattier 14

N Today at 5:30 PM by ehuseyinyigit

Source: les dattes à Dattier

Is it true that $\forall n \in \mathbb N^*, (24^n \times B \mod A) \mod 2 = 0$ ?

A=1728400904217815186787639216753921417860004366580219212750904
024377969478249664644267971025952530803647043121025959018172048
336953969062151534282052863307398281681465366665810775710867856
720572225880311472925624694183944650261079955759251769111321319
421445397848518597584590900951222557860592579005088853698315463
815905425095325508106272375728975

B=2275643401548081847207782760491442295266487354750527085289354
965376765188468052271190172787064418854789322484305145310707614
546573398182642923893780527037224143380886260467760991228567577
953725945090125797351518670892779468968705801340068681556238850
340398780828104506916965606659768601942798676554332768254089685
307970609932846902

14 replies

Dattier

Mar 10, 2025

ehuseyinyigit

Today at 5:30 PM

J

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iran tst 2018 geometry

Etemadi 10

N Today at 5:05 PM by amirhsz

Source: Iranian TST 2018, second exam day 2, problem 5

Let $\omega$ be the circumcircle of isosceles triangle $ABC$ ( $AB=AC$ ). Points $P$ and $Q$ lie on $\omega$ and $BC$ respectively such that $AP=AQ$ . $AP$ and $BC$ intersect at $R$ . Prove that the tangents from $B$ and $C$ to the incircle of $\triangle AQR$ (different from $BC$ ) are concurrent on $\omega$ .

Proposed by Ali Zamani, Hooman Fattahi

10 replies

Etemadi

Apr 17, 2018

amirhsz

Today at 5:05 PM

J