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Site Support Tech support and questions about AoPS classes and materials
Tech support and questions about AoPS classes and materials
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k a July Highlights and 2025 AoPS Online Class Information
jwelsh   0
Tuesday at 2:14 PM
We are halfway through summer, so be sure to carve out some time to keep your skills sharp and explore challenging topics at AoPS Online and our AoPS Academies (including the Virtual Campus)!

[list][*]Over 60 summer classes are starting at the Virtual Campus on July 7th - check out the math and language arts options for middle through high school levels.
[*]At AoPS Online, we have accelerated sections where you can complete a course in half the time by meeting twice/week instead of once/week, starting on July 8th:
[list][*]MATHCOUNTS/AMC 8 Basics
[*]MATHCOUNTS/AMC 8 Advanced
[*]AMC Problem Series[/list]
[*]Plus, AoPS Online has a special seminar July 14 - 17 that is outside the standard fare: Paradoxes and Infinity
[*]We are expanding our in-person AoPS Academy locations - are you looking for a strong community of problem solvers, exemplary instruction, and math and language arts options? Look to see if we have a location near you and enroll in summer camps or academic year classes today! New locations include campuses in California, Georgia, New York, Illinois, and Oregon and more coming soon![/list]

MOP (Math Olympiad Summer Program) just ended and the IMO (International Mathematical Olympiad) is right around the corner! This year’s IMO will be held in Australia, July 10th - 20th. Congratulations to all the MOP students for reaching this incredible level and best of luck to all selected to represent their countries at this year’s IMO! Did you know that, in the last 10 years, 59 USA International Math Olympiad team members have medaled and have taken over 360 AoPS Online courses. Take advantage of our Worldwide Online Olympiad Training (WOOT) courses
and train with the best! Please note that early bird pricing ends August 19th!
Are you tired of the heat and thinking about Fall? You can plan your Fall schedule now with classes at either AoPS Online, AoPS Academy Virtual Campus, or one of our AoPS Academies around the US.

Our full course list for upcoming classes is below:
All classes start 7:30pm ET/4:30pm PT unless otherwise noted.

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0 replies
jwelsh
Tuesday at 2:14 PM
0 replies
[PMO26 Areas] I.15 Permutations + divisibility
aops-g5-gethsemanea2   4
N 44 minutes ago by BinariouslyRandom
How many ways are there to arrange all the digits in the number 629,999,999 so that the resulting number is divisible by 37?
4 replies
aops-g5-gethsemanea2
Jan 26, 2025
BinariouslyRandom
44 minutes ago
REQUEST LOCK
KangarooPrecise   23
N an hour ago by stjwyl
On my username, why is there 3 dots after it, when 2 letters are missing?
23 replies
KangarooPrecise
Yesterday at 1:24 PM
stjwyl
an hour ago
I’m desperate, Can someone pls help me out?
Dakrya   2
N 3 hours ago by alexheinis
Let A = {1,5,7,{1},{7},{1,5},{5,7}}
Let G = {B⊂P(A)| n(A-B) = 4} when P(A) is a power set of set A. Find n(G)
2 replies
Dakrya
Jun 27, 2025
alexheinis
3 hours ago
FOUR PROBLEMS
CurlyFalcon55   3
N 5 hours ago by LoreleiA
There are four homework problems that are REALLY BUGGING ME because I CANNOT FIND THE ANSWER. :mad:
Can I make a forum where I can ask questions about these problems? Can I make one as long as it follows the AoPS Honor Code and the Terms of Service? (I can explicitly state that in the forum.)
If I have to I can make it private with a few select people. Or can I make a blog version? ;)

I know this was kind of already adressed in the "Is there a forum?" thread, but that was for existing forums. This is for a potential new public/private forum. :)

Read before replying

IMAGE
3 replies
CurlyFalcon55
Yesterday at 7:34 PM
LoreleiA
5 hours ago
I can't type into boxes during lessons
HADP   5
N 5 hours ago by LoreleiA
Recently, I have been experiencing an issue where i can't type into the boxes that professors post during a lesson. I can't input an answer and i've tried refreshing multiple times and it doesn't work. This has happened in many lessons in a row. Please help! Also, is there a way to make Aops dark mode?
5 replies
HADP
Tuesday at 5:17 PM
LoreleiA
5 hours ago
Trigonometry
Maaaaaaath   4
N Yesterday at 8:28 PM by vanstraelen
In a geometric progression we have $ a_1 = \sin x $ , $a_2 = \cos x $ and $a_3 = \tan x$ .Which term of this progression is equal to $1+\cos x$ ?
4 replies
Maaaaaaath
Yesterday at 6:40 PM
vanstraelen
Yesterday at 8:28 PM
inequality
adamath4ever   2
N Yesterday at 7:37 PM by adamath4ever
$0<a,b,c<1$ real numbers ; such that : $2(a+b+c)+4abc = 3(ab +ac+bc)+1$
Prove that: $a+b+c<3/4$
2 replies
adamath4ever
Yesterday at 5:09 PM
adamath4ever
Yesterday at 7:37 PM
Trigonometry
Maaaaaaath   0
Yesterday at 6:39 PM
In a geometric progression we have $ a_1 = \sin x $ , $a_2 = \cos x $ and $a_3 = \tan x$ .Which term of this progression is equal to $1+\cos x$ ?
0 replies
Maaaaaaath
Yesterday at 6:39 PM
0 replies
Just so SS knows....
jmr2010   4
N Yesterday at 6:25 PM by CurlyFalcon55
If you open a PM, specify yourself, and put something there, then hit send, it says you are automatically included and if you want to talk to yourself, leave the to box blank. If you leave the box blank, it won't send the PM because the to box is blank
4 replies
jmr2010
Yesterday at 3:28 PM
CurlyFalcon55
Yesterday at 6:25 PM
2016 preRMO p9, 4 b^2 -a^3 where a,b roots of x^2 + x - 3 = 0
parmenides51   9
N Yesterday at 5:44 PM by fathersayno
Let $a$ and $b$ be the roots of the equation $x^2 + x - 3 = 0$. Find the value of the expression $4b^2 -a^3$.
9 replies
parmenides51
Aug 9, 2019
fathersayno
Yesterday at 5:44 PM
random thing I found
sv_legend   1
N Yesterday at 5:27 PM by nudinhtien
This is probably useless but I found that:

If you have 2 squares $n^2$ and $(n+k)^2$, the distance between them is $2(n+1)-1 + 2(n+2)-1 + 2(n+3)-1+...+2(n+k-1)-1+2(n+k)-1$ because I know the distance between $(n-1)^2$ and $n^2$ is $2n-1$ or in other words the $n$th odd number so I'm just adding all of the distances between consecutive squares. (wait can't you just use difference of squares) Yeah so this is just a way longer way to find distance between squares rather than just using difference of squares and factoring.


I hope this is actually true otherwise I will lose so much aura
1 reply
sv_legend
Yesterday at 4:30 PM
nudinhtien
Yesterday at 5:27 PM
Find line EF
Darealzolt   0
Yesterday at 5:17 PM
4 Points \(A,B,C,D\) lie on a circle in that order shown, the extension of \(AB\) meets the extension of \(DC\) at \(E\), the extension of of \(AD\) meets the extension of \(BC\) at \(F\). Let \(EP\) and \(FQ\) be tangents with \(P\) and \(Q\) being the tangent points. If \(EP=60\), and \(FQ = 63\), find the measure of \(EF\)
0 replies
Darealzolt
Yesterday at 5:17 PM
0 replies
[PMO25 Qualifying I.8] Length of Diagonal
kae_3   1
N Yesterday at 4:05 PM by vanstraelen
The sides of a convex quadrilateral have lengths $12$cm, $12$cm, $16$cm, and $16$cm, and they are arranged so that there are no pairs of parallel sides. If one of the diagonals is $20$cm long, and the length of the other diagonal is a rational number, what is the length of the other diagonal?

$\text{(a) }\frac{48}{5}\text{ cm}\qquad\text{(b) }\frac{84}{5}\text{ cm}\qquad\text{(c) }\frac{96}{5}\text{ cm}\qquad\text{(d) }\frac{108}{5}\text{ cm}$

Answer Confirmation
1 reply
kae_3
Feb 23, 2025
vanstraelen
Yesterday at 4:05 PM
Root of Unity filtering
Kyj9981   5
N Yesterday at 4:02 PM by Andyluo
Evaluate
$\binom{2017}{0}+\binom{2017}{3}+\cdots+\binom{2017}{2016}$

Source: Ray Li Handout on Roots of Unity

Answer
5 replies
Kyj9981
Yesterday at 3:22 PM
Andyluo
Yesterday at 4:02 PM
k 9 Strikethrough does not work with other sizes.
Sotowa   3
N Mar 23, 2023 by yiz76
(Yes, this is a BBCode issue, not AoPS, but AoPS might be able to implement something to accommodate for this.)

Strikethrough ([s]text[/s]) does not work on text that is a different size ([size=InsertNumberHere]text[/size]) if the strikethrough tags are on the outside (thanks aidan0626).

Too small text
Small text
Medium text
Large text
Too large text

If you would like to test this, please go here. Keep this thread for discussion of the bug, not testing.
3 replies
Sotowa
Mar 23, 2023
yiz76
Mar 23, 2023
Strikethrough does not work with other sizes.
G H J
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
Sotowa
9245 posts
#1
Y by
9Poll:
Can you reproduce this bug?
31 Votes
74%
(23)
10%
(3)
16%
(5)
You must be signed in to vote.
(Yes, this is a BBCode issue, not AoPS, but AoPS might be able to implement something to accommodate for this.)

Strikethrough ([s]text[/s]) does not work on text that is a different size ([size=InsertNumberHere]text[/size]) if the strikethrough tags are on the outside (thanks aidan0626).

Too small text
Small text
Medium text
Large text
Too large text

If you would like to test this, please go here. Keep this thread for discussion of the bug, not testing.
This post has been edited 1 time. Last edited by Sotowa, Mar 25, 2023, 2:55 AM
Z Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
aayr
2480 posts
#2
Y by
this is an html issue, because the html code uses <strike> instead of the css code
text-decoration: line-through;
which if added, does work as intended with the different font sizes.
Z Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
aidan0626
2033 posts
#3
Y by
if you do it like [size=200][s]test[/s][/size] instead of [s][size=200]test[/size][/s], you get test, instead of test
Z Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
yiz76
1403 posts
#4
Y by
hihihihihihihihihi

Summary of the problem: Strikethrough is bugged when using with size tags
Page URL: Aops community
Steps to reproduce:
1. Open create post
2. Put a text sizer instead of strikethrough like this: [s][size=200]bruh[/size][/s]
Expected behavior: The strikethrough is aligned correctly
Frequency: 100%
Operating system: All of them
Browser, including version: All of them
Additional information:
Z Y
G
H
=
a