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k a March Highlights and 2025 AoPS Online Class Information
jlacosta   0
Mar 2, 2025
March is the month for State MATHCOUNTS competitions! Kudos to everyone who participated in their local chapter competitions and best of luck to all going to State! Join us on March 11th for a Math Jam devoted to our favorite Chapter competition problems! Are you interested in training for MATHCOUNTS? Be sure to check out our AMC 8/MATHCOUNTS Basics and Advanced courses.

Are you ready to level up with Olympiad training? Registration is open with early bird pricing available for our WOOT programs: MathWOOT (Levels 1 and 2), CodeWOOT, PhysicsWOOT, and ChemWOOT. What is WOOT? WOOT stands for Worldwide Online Olympiad Training and is a 7-month high school math Olympiad preparation and testing program that brings together many of the best students from around the world to learn Olympiad problem solving skills. Classes begin in September!

Do you have plans this summer? There are so many options to fit your schedule and goals whether attending a summer camp or taking online classes, it can be a great break from the routine of the school year. Check out our summer courses at AoPS Online, or if you want a math or language arts class that doesn’t have homework, but is an enriching summer experience, our AoPS Virtual Campus summer camps may be just the ticket! We are expanding our locations for our AoPS Academies across the country with 15 locations so far and new campuses opening in Saratoga CA, Johns Creek GA, and the Upper West Side NY. Check out this page for summer camp information.

Be sure to mark your calendars for the following events:
[list][*]March 5th (Wednesday), 4:30pm PT/7:30pm ET, HCSSiM Math Jam 2025. Amber Verser, Assistant Director of the Hampshire College Summer Studies in Mathematics, will host an information session about HCSSiM, a summer program for high school students.
[*]March 6th (Thursday), 4:00pm PT/7:00pm ET, Free Webinar on Math Competitions from elementary through high school. Join us for an enlightening session that demystifies the world of math competitions and helps you make informed decisions about your contest journey.
[*]March 11th (Tuesday), 4:30pm PT/7:30pm ET, 2025 MATHCOUNTS Chapter Discussion MATH JAM. AoPS instructors will discuss some of their favorite problems from the MATHCOUNTS Chapter Competition. All are welcome!
[*]March 13th (Thursday), 4:00pm PT/7:00pm ET, Free Webinar about Summer Camps at the Virtual Campus. Transform your summer into an unforgettable learning adventure! From elementary through high school, we offer dynamic summer camps featuring topics in mathematics, language arts, and competition preparation - all designed to fit your schedule and ignite your passion for learning.[/list]
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0 replies
jlacosta
Mar 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
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How to convert base numbers directly without using base 10
DSL13   9
N a few seconds ago by gauss202
I don't understand the topic of how you convert bases directly without going from base 10 to the base that I desire. How do I get from one base to another without the use of base 10?

I watched videos on it but I don't really get the idea.
9 replies
+2 w
DSL13
Mar 11, 2021
gauss202
a few seconds ago
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3D Geometry Problem
ReticulatedPython   17
N 12 minutes ago by ReticulatedPython
A sphere with radius $1$ is centered at the apex of a right square pyramid with base length $2$ and height $1.$ The volume of the space where the sphere overlaps with the pyramid can be expressed in the form $k\pi.$ Find $k.$

Hint

Formulas
17 replies
ReticulatedPython
Yesterday at 4:05 PM
ReticulatedPython
12 minutes ago
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Problem of the week
evt917   30
N 16 minutes ago by evt917
Whenever possible, I will be posting problems twice a week! They will be roughly of AMC 8 difficulty. Have fun solving! Also, these problems are all written by myself!

First problem:

$20^{16}$ has how many digits?
30 replies
evt917
Mar 5, 2025
evt917
16 minutes ago
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China Mathematical Olympiad 1993 problem5
jred   3
N 35 minutes ago by iStud
Source: China Mathematical Olympiad 1993 problem5
$10$ students bought some books in a bookstore. It is known that every student bought exactly three kinds of books, and any two of them shared at least one kind of book. Determine, with proof, how many students bought the most popular book at least? (Note: the most popular book means most students bought this kind of book)
3 replies
jred
Sep 23, 2013
iStud
35 minutes ago
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Angle problem
FlyingDragon21   13
N an hour ago by Alex_Yang
In Isosceles triangle ABC where AB equals AC and point D lies on line AB, line CD splits line AB so that AD equals BC. If angle BAC is 20 degrees, what is the measure of angle DCA?
13 replies
FlyingDragon21
Yesterday at 11:36 PM
Alex_Yang
an hour ago
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x and o game, in an infinite grid of regular triangles
parmenides51   5
N an hour ago by Lil_flip38
Source: Norwegian Mathematical Olympiad 2017 - Abel Competition p3b
In an infinite grid of regular triangles, Niels and Henrik are playing a game they made up.
Every other time, Niels picks a triangle and writes $\times$ in it, and every other time, Henrik picks a triangle where he writes a $o$. If one of the players gets four in a row in some direction (see figure), he wins the game.
Determine whether one of the players can force a victory.
IMAGE
5 replies
parmenides51
Sep 3, 2019
Lil_flip38
an hour ago
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BMN is equilateral iff rectangle ABCD is square
parmenides51   4
N an hour ago by Tsikaloudakis
Source: 2004 Romania NMO SL - Shortlist VII-VIII p8 https://artofproblemsolving.com/community/c3950157_
Consider a point $M$ on the diagonal $BD$ of a given rectangle $ABCD$, such that $\angle AMC = \angle CMD$. The point $N$ is the intersection point between $AM$ and the parallel line to $CM$ that contains $B$. Prove that the triangle $BMN$ is equilateral if and only if $ABCD$ is a square.

Valentin Vornicu
4 replies
parmenides51
Sep 16, 2024
Tsikaloudakis
an hour ago
J
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Loop of Logarithms
scls140511   10
N an hour ago by SomeonecoolLovesMaths
Source: 2024 China Round 1 (Gao Lian)
Round 1

1 Real number $m>1$ satisfies $\log_9 \log_8 m =2024$. Find the value of $\log_3 \log_2 m$.
10 replies
scls140511
Sep 8, 2024
SomeonecoolLovesMaths
an hour ago
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Proving a kite
Bugi   4
N 2 hours ago by ali123456
Source: Serbian JBTST 3, Day 2
Let $ ABCD$ be a convex quadrilateral, such that

$ \angle CBD=2\cdot\angle ADB, \angle ABD=2\cdot\angle CDB$ and $ AB=CB$.

Prove that quadrilateral $ ABCD$ is a kite.
4 replies
Bugi
May 31, 2009
ali123456
2 hours ago
J
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Inequality
Marinchoo   6
N 2 hours ago by sqing
If $abc=1$ prove that $8(a^3+b^3+c^3) \geq 3(a^2+bc)(b^2+ac)(c^2+ab)$
6 replies
Marinchoo
Apr 28, 2020
sqing
2 hours ago
J
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Interesting inequality
sqing   4
N 2 hours ago by sqing
Source: Own
Let $ a,b,c\geq 2 . $ Prove that
$$(a^2-1)(b-1)(c^2-1) -\frac{9}{4}abc\geq -9$$$$(a^2-1)(b-1)(c^2-1) -\frac{11}{5}abc\geq -\frac{43}{5}$$$$(a^2-1)(b-1)(c^2-1) -2abc\geq -7$$$$(a-1)(b^2-1)(c-1) -\frac{3}{4}abc\geq -3$$$$(a-1)(b^2-1)(c-1) -\frac{3}{5}abc\geq -\frac{9}{5}$$$$(a-1)(b^2-1)(c-1) -\frac{1}{2}abc\geq -1$$
4 replies
sqing
4 hours ago
sqing
2 hours ago
J
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Orthocentre is collinear with two tangent points
vladimir92   42
N 2 hours ago by AshAuktober
Source: Chinese MO 1996
Let $\triangle{ABC}$ be a triangle with orthocentre $H$. The tangent lines from $A$ to the circle with diameter $BC$ touch this circle at $P$ and $Q$. Prove that $H,P$ and $Q$ are collinear.
42 replies
vladimir92
Jul 29, 2010
AshAuktober
2 hours ago
J
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Problem 4
den_thewhitelion   3
N 2 hours ago by DensSv
Source: Second Romanian JBMO TST 2016
We have a 4x4 board.All 1x1 squares are white.A move is changing colours of all squares of a 1x3 rectangle from black to white and from white to black.It is possible to make all the 1x1 squares black after several moves?
3 replies
den_thewhitelion
Jun 15, 2016
DensSv
2 hours ago
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Find the period
Anto0110   2
N 2 hours ago by YaoAOPS
Let $a_1, a_2, ..., a_k, ...$ be a sequence that consists of an initial block of $p$ positive distinct integers that then repeat periodically. This means that $\{a_1, a_2, \dots, a_p\}$ are $p$ distinct positive integers and $a_{n+p}=a_n$ for every positive integer $n$. The terms of the sequence are not known and the goal is to find the period $p$. To do this, at each move it possible to reveal the value of a term of the sequence at your choice.
If $p$ is one of the first $k$ prime numbers, find for which values of $k$ there exist a strategy that allows to find $p$ revealing at most $8$ terms of the sequence.
2 replies
Anto0110
Yesterday at 7:37 PM
YaoAOPS
2 hours ago
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9 What should I do..?
Leeoz   6
N Mar 17, 2025 by sadas123
So, there is a very important decision.. and I have decided to asked all of the people on AoPS :P

I am going to MathCounts nats, but there is the MathCon a day before the competition. It there anything I will miss by just going to MathCounts right on the day of the contest, or is it worth it to go to MathCon, even if I will have to leave before the awards.

Just want your ideas and opinions for this :)
also pls say if there is something that I will miss in MathCounts before the actual contest
6 replies
Leeoz
Mar 17, 2025
sadas123
Mar 17, 2025
J
What should I do..?
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Reveal topic tags
MATHCOUNTS
poll
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Leeoz
143 posts
Leeoz
#1 h  Mar 17, 2025, 6:17 AM
Y by
9Poll:
What should I do?
48 Votes
69%
(33)
31%
(15)
Hide Results Show Results
You must be signed in to vote.
So, there is a very important decision.. and I have decided to asked all of the people on AoPS :P

I am going to MathCounts nats, but there is the MathCon a day before the competition. It there anything I will miss by just going to MathCounts right on the day of the contest, or is it worth it to go to MathCon, even if I will have to leave before the awards.

Just want your ideas and opinions for this :)
also pls say if there is something that I will miss in MathCounts before the actual contest
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MathPerson12321
3616 posts
MathPerson12321
#2 h  Mar 17, 2025, 6:19 AM
Y by
The written round for Mathcounts is the day after you are supposed to arrive.
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Leeoz
143 posts
Leeoz
#3 h  Mar 17, 2025, 6:36 AM
Y by
MathPerson12321 wrote:
The written round for Mathcounts is the day after you are supposed to arrive.

the day before the written round is mathcon
is there anything ill miss if i got there
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Andyluo
851 posts
Andyluo
#4 h  Mar 17, 2025, 11:29 AM
Y by
mathcon doesn't seem to important, but you could go
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Rice_Farmer
879 posts
Rice_Farmer
#5 h  Mar 17, 2025, 1:05 PM
Y by
the whole concept of mathcon in the first place is kinda stupid for a contest (lower grades get easier contests) and MathCOUNTS is way more prestitigous
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MathRook7817
609 posts
MathRook7817
#6 h  Mar 17, 2025, 2:11 PM
Y by
MATHCOUNTS is much more fun i think
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sadas123
1057 posts
sadas123
#7 h  Mar 17, 2025, 2:13 PM
Y by
MATHCOUNT is better. why is my Auto correct make everything capitalized?
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