Plan ahead for the next school year. Schedule your class today!

G
Topic
First Poster
Last Poster
k a July Highlights and 2025 AoPS Online Class Information
jwelsh   0
Jul 1, 2025
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.

Introductory: Grades 5-10

Prealgebra 1 Self-Paced

Prealgebra 1
Wednesday, Jul 16 - Oct 29
Sunday, Aug 17 - Dec 14
Tuesday, Aug 26 - Dec 16
Friday, Sep 5 - Jan 16
Monday, Sep 8 - Jan 12
Tuesday, Sep 16 - Jan 20 (4:30 - 5:45 pm ET/1:30 - 2:45 pm PT)
Sunday, Sep 21 - Jan 25
Thursday, Sep 25 - Jan 29
Wednesday, Oct 22 - Feb 25
Tuesday, Nov 4 - Mar 10
Friday, Dec 12 - Apr 10

Prealgebra 2 Self-Paced

Prealgebra 2
Friday, Jul 25 - Nov 21
Sunday, Aug 17 - Dec 14
Tuesday, Sep 9 - Jan 13
Thursday, Sep 25 - Jan 29
Sunday, Oct 19 - Feb 22
Monday, Oct 27 - Mar 2
Wednesday, Nov 12 - Mar 18

Introduction to Algebra A Self-Paced

Introduction to Algebra A
Tuesday, Jul 15 - Oct 28
Sunday, Aug 17 - Dec 14
Wednesday, Aug 27 - Dec 17
Friday, Sep 5 - Jan 16
Thursday, Sep 11 - Jan 15
Sunday, Sep 28 - Feb 1
Monday, Oct 6 - Feb 9
Tuesday, Oct 21 - Feb 24
Sunday, Nov 9 - Mar 15
Friday, Dec 5 - Apr 3

Introduction to Counting & Probability Self-Paced

Introduction to Counting & Probability
Wednesday, Jul 2 - Sep 17
Sunday, Jul 27 - Oct 19
Monday, Aug 11 - Nov 3
Wednesday, Sep 3 - Nov 19
Sunday, Sep 21 - Dec 14 (1:00 - 2:30 pm ET/10:00 - 11:30 am PT)
Friday, Oct 3 - Jan 16
Sunday, Oct 19 - Jan 25
Tuesday, Nov 4 - Feb 10
Sunday, Dec 7 - Mar 8

Introduction to Number Theory
Tuesday, Jul 15 - Sep 30
Wednesday, Aug 13 - Oct 29
Friday, Sep 12 - Dec 12
Sunday, Oct 26 - Feb 1
Monday, Dec 1 - Mar 2

Introduction to Algebra B Self-Paced

Introduction to Algebra B
Friday, Jul 18 - Nov 14
Thursday, Aug 7 - Nov 20
Monday, Aug 18 - Dec 15
Sunday, Sep 7 - Jan 11
Thursday, Sep 11 - Jan 15
Wednesday, Sep 24 - Jan 28
Sunday, Oct 26 - Mar 1
Tuesday, Nov 4 - Mar 10
Monday, Dec 1 - Mar 30

Introduction to Geometry
Monday, Jul 14 - Jan 19
Wednesday, Aug 13 - Feb 11
Tuesday, Aug 26 - Feb 24
Sunday, Sep 7 - Mar 8
Thursday, Sep 11 - Mar 12
Wednesday, Sep 24 - Mar 25
Sunday, Oct 26 - Apr 26
Monday, Nov 3 - May 4
Friday, Dec 5 - May 29

Paradoxes and Infinity
Mon, Tue, Wed, & Thurs, Jul 14 - Jul 16 (meets every day of the week!)
Sat & Sun, Sep 13 - Sep 14 (1:00 - 4:00 PM PT/4:00 - 7:00 PM ET)

Intermediate: Grades 8-12

Intermediate Algebra
Sunday, Jul 13 - Jan 18
Thursday, Jul 24 - Jan 22
Friday, Aug 8 - Feb 20
Tuesday, Aug 26 - Feb 24
Sunday, Sep 28 - Mar 29
Wednesday, Oct 8 - Mar 8
Sunday, Nov 16 - May 17
Thursday, Dec 11 - Jun 4

Intermediate Counting & Probability
Sunday, Sep 28 - Feb 15
Tuesday, Nov 4 - Mar 24

Intermediate Number Theory
Wednesday, Sep 24 - Dec 17

Precalculus
Wednesday, Aug 6 - Jan 21
Tuesday, Sep 9 - Feb 24
Sunday, Sep 21 - Mar 8
Monday, Oct 20 - Apr 6
Sunday, Dec 14 - May 31

Advanced: Grades 9-12

Calculus
Sunday, Sep 7 - Mar 15
Wednesday, Sep 24 - Apr 1
Friday, Nov 14 - May 22

Contest Preparation: Grades 6-12

MATHCOUNTS/AMC 8 Basics
Tues & Thurs, Jul 8 - Aug 14 (meets twice a week!)
Sunday, Aug 17 - Nov 9
Wednesday, Sep 3 - Nov 19
Tuesday, Sep 16 - Dec 9
Sunday, Sep 21 - Dec 14 (1:00 - 2:30 pm ET/10:00 - 11:30 am PT)
Monday, Oct 6 - Jan 12
Thursday, Oct 16 - Jan 22
Tues, Thurs & Sun, Dec 9 - Jan 18 (meets three times a week!)

MATHCOUNTS/AMC 8 Advanced
Tues & Thurs, Jul 8 - Aug 14 (meets twice a week!)
Sunday, Aug 17 - Nov 9
Tuesday, Aug 26 - Nov 11
Thursday, Sep 4 - Nov 20
Friday, Sep 12 - Dec 12
Monday, Sep 15 - Dec 8
Sunday, Oct 5 - Jan 11
Tues, Thurs & Sun, Dec 2 - Jan 11 (meets three times a week!)
Mon, Wed & Fri, Dec 8 - Jan 16 (meets three times a week!)

AMC 10 Problem Series
Tues & Thurs, Jul 8 - Aug 14 (meets twice a week!)
Sunday, Aug 10 - Nov 2
Thursday, Aug 14 - Oct 30
Tuesday, Aug 19 - Nov 4
Mon & Wed, Sep 15 - Oct 22 (meets twice a week!)
Mon, Wed & Fri, Oct 6 - Nov 3 (meets three times a week!)
Tue, Thurs & Sun, Oct 7 - Nov 2 (meets three times a week!)

AMC 10 Final Fives
Friday, Aug 15 - Sep 12
Sunday, Sep 7 - Sep 28
Tuesday, Sep 9 - Sep 30
Monday, Sep 22 - Oct 13
Sunday, Sep 28 - Oct 19 (1:00 - 2:30 pm ET/10:00 - 11:30 am PT)
Wednesday, Oct 8 - Oct 29
Thursday, Oct 9 - Oct 30

AMC 12 Problem Series
Wednesday, Aug 6 - Oct 22
Sunday, Aug 10 - Nov 2
Monday, Aug 18 - Nov 10
Mon & Wed, Sep 15 - Oct 22 (meets twice a week!)
Tues, Thurs & Sun, Oct 7 - Nov 2 (meets three times a week!)

AMC 12 Final Fives
Thursday, Sep 4 - Sep 25
Sunday, Sep 28 - Oct 19
Tuesday, Oct 7 - Oct 28

AIME Problem Series A
Thursday, Oct 23 - Jan 29

AIME Problem Series B
Tuesday, Sep 2 - Nov 18

F=ma Problem Series
Tuesday, Sep 16 - Dec 9
Friday, Oct 17 - Jan 30

WOOT Programs
Visit the pages linked for full schedule details for each of these programs!


MathWOOT Level 1
MathWOOT Level 2
ChemWOOT
CodeWOOT
PhysicsWOOT


Programming

Introduction to Programming with Python
Thursday, Aug 14 - Oct 30
Sunday, Sep 7 - Nov 23
Tuesday, Dec 2 - Mar 3

Intermediate Programming with Python
Friday, Oct 3 - Jan 16

USACO Bronze Problem Series
Wednesday, Sep 3 - Dec 3
Thursday, Oct 30 - Feb 5
Tuesday, Dec 2 - Mar 3

Physics

Introduction to Physics
Tuesday, Sep 2 - Nov 18
Sunday, Oct 5 - Jan 11
Wednesday, Dec 10 - Mar 11

Physics 1: Mechanics
Sunday, Sep 21 - Mar 22
Sunday, Oct 26 - Apr 26
0 replies
jwelsh
Jul 1, 2025
0 replies
Factorial fraction
Silverfalcon   34
N an hour ago by Munji1
$\frac{(3!)!}{3!} =$

$\text{(A)}\ 1 \qquad \text{(B)}\ 2 \qquad \text{(C)}\ 6\qquad \text{(D)}\ 40\qquad \text{(E)}\ 120$
34 replies
Silverfalcon
Nov 21, 2005
Munji1
an hour ago
9 science bowl
valenbb   19
N an hour ago by Munji1
i would like to know if the math kids on AoPS did science bowl

for me my team made it to nationals but we didn't do that good there, it was still a really fun experience tho :)
19 replies
valenbb
Sunday at 6:27 PM
Munji1
an hour ago
Creative Geometry Problem
giratina3   12
N 3 hours ago by cheltstudent
Let there be a triangle ABC. Let BX bisect CBA, CY bisect ACB, and XY parallel to BC. If AB = 12, BC = 24, and AC = 18, then what is the perimeter of the triangle AXY?

The hint gives away most of the problem, so make sure you consider the problem for a long time before reading it :thumbup:

(The answer is an integer to you coordinate bashers :play_ball:)

Hint
12 replies
giratina3
Jul 12, 2025
cheltstudent
3 hours ago
Scores on Contests for Ya'll to submit! (everyone be as honest as possible)
NEILDASEAL_12345   87
N 4 hours ago by slightly_irrational
What are yall's most recent scores on mathCON, AMC 8 and other things? I just wanna know how I'm holding up and if my scores are good! This is the end of my first year in contest math, and I've always been gifted, but can someone tell me if these scores are good? MATHCON: 240
AMC 8: 19 QUESTIONS
AMC 10: 16 QUESTIONS
btw I'm going to 7th grade

EDIT: Y'all I mean 16 questions right on the AMC 10, I'm way too lazy to scroll and find the number of points lol
EDIT: Math Kangaroo: I forgot the score, but I got like 30th National
87 replies
NEILDASEAL_12345
Jul 10, 2025
slightly_irrational
4 hours ago
No more topics!
Modulo Case Work Problem
PikaVee   7
N Jun 1, 2025 by PikaVee
(Thanks Random Stranger for the idea and I will be making it so it is extremely specific to your solution.)
We are playing Pokemon Scarlet and Violet and you are fighting a friend. You and your friend don't have any items at all and the pokemon does not have any held items. Your friend challenges you to a battle because he just said nah I'd win.

You two start the battle using only one Pokemon each which neither of you knows the type of the other. Luckily he had used a level 28 Squirtle and you had used a level 25 Pikachu. Surprisingly both of the Pokemon each have one HP. Your Pikachu has a move set of one single move of Thunder with 10/10 PP and has 1 HP because you forgot to go to the Pokemon center. Your Pikachu also has a bad IV stat in speed with 1/15 and the 252 EV speed stat of the Squirtle combined with a perfect IV stat in speed makes it so it guarantees to always out speed your move. To account for that he made his Squirtle have 1 HP on purpose for absolutely no reason.

After he saw what kind of moves you have and since that person was so cocky and confident that they decided to gamble all their moves with each having an equal chance of being used. Their Squirtle has a move set of Protect 10 PP which has 100% chance of being used and has has the success probability multiplied by 1/3 every time it is being used (Meaning the second time it is being used has a 33% chance of succeeding and a third time it will be 11%. This also ignores the rules of how the move is regularly used by making the 4th move 1/27 instead of it being a guaranteed fail and so on.), Tackle which has a 100% chance to hit having 10/35 PP , Water Gun which has a 100% chance of hitting with 10/25 and Rain Dance with 5/5 PP and 100% chance of being used. If the amount of PP reaches 0 it will be unavailable for the rest of the fight meaning that the probability for each other move to be used goes from 25% all the way to 33%.

For everyone who wants to solve the easy part. If the probability that Squirtle will survive turn 1 when simplified is a/b then what is a+b?

Alright so for Squirtle to survive turn one then we try to find out how Squirte will faint at turn one. First of all Pikachu needs to hit Thunder bolt at a 70% chance then get a 25% chance that the Squirtle will use Rain Dance so that the Squirtle will not faint the Pikachu because it didn't attack. Another possible option is for it to choose Water Gun and miss so it would be a 70% * 25% * 5% chance for Pikachu to faint Squirtle. 70% = \frac{7}{10}, 25% = \frac{1}{4}, and 5% = \frac{1}{20} So the complement of what we are trying to find is $\frac{7}{10}*\frac{1}{4}+\frac{7}{10}*\frac{1}{4}*\frac{1}{20}=\frac{7}{10*4}+\frac{7}{10*4*20}=\frac{7}{40}+\frac{7}{800}=\frac{140}{800}+\frac{7}{800}=\frac{147}{800}$. The complement of this would be $1-\frac{147}{800}$ or $\frac{653}{800}$. The final thing we can do is to make sure it is simplified and add the numerator and the denominator which is $653$ and $800$ so $653+800=1453$ This should be final answer. (Mathdash rating 800)

For the very hard question, What is the probability that the Squirtle will win this fight? (This is going to be a very long arithmetic series with a lot of cases. The max amount of turns this fight can have is 11 turns.)
7 replies
PikaVee
May 28, 2025
PikaVee
Jun 1, 2025
Modulo Case Work Problem
G H J
G H BBookmark kLocked kLocked NReply
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
PikaVee
22 posts
#1 • 1 Y
Y by GA34-261
(Thanks Random Stranger for the idea and I will be making it so it is extremely specific to your solution.)
We are playing Pokemon Scarlet and Violet and you are fighting a friend. You and your friend don't have any items at all and the pokemon does not have any held items. Your friend challenges you to a battle because he just said nah I'd win.

You two start the battle using only one Pokemon each which neither of you knows the type of the other. Luckily he had used a level 28 Squirtle and you had used a level 25 Pikachu. Surprisingly both of the Pokemon each have one HP. Your Pikachu has a move set of one single move of Thunder with 10/10 PP and has 1 HP because you forgot to go to the Pokemon center. Your Pikachu also has a bad IV stat in speed with 1/15 and the 252 EV speed stat of the Squirtle combined with a perfect IV stat in speed makes it so it guarantees to always out speed your move. To account for that he made his Squirtle have 1 HP on purpose for absolutely no reason.

After he saw what kind of moves you have and since that person was so cocky and confident that they decided to gamble all their moves with each having an equal chance of being used. Their Squirtle has a move set of Protect 10 PP which has 100% chance of being used and has has the success probability multiplied by 1/3 every time it is being used (Meaning the second time it is being used has a 33% chance of succeeding and a third time it will be 11%. This also ignores the rules of how the move is regularly used by making the 4th move 1/27 instead of it being a guaranteed fail and so on.), Tackle which has a 100% chance to hit having 10/35 PP , Water Gun which has a 100% chance of hitting with 10/25 and Rain Dance with 5/5 PP and 100% chance of being used. If the amount of PP reaches 0 it will be unavailable for the rest of the fight meaning that the probability for each other move to be used goes from 25% all the way to 33%.

For everyone who wants to solve the easy part. If the probability that Squirtle will survive turn 1 when simplified is a/b then what is a+b?

Alright so for Squirtle to survive turn one then we try to find out how Squirte will faint at turn one. First of all Pikachu needs to hit Thunder bolt at a 70% chance then get a 25% chance that the Squirtle will use Rain Dance so that the Squirtle will not faint the Pikachu because it didn't attack. Another possible option is for it to choose Water Gun and miss so it would be a 70% * 25% * 5% chance for Pikachu to faint Squirtle. 70% = \frac{7}{10}, 25% = \frac{1}{4}, and 5% = \frac{1}{20} So the complement of what we are trying to find is $\frac{7}{10}*\frac{1}{4}+\frac{7}{10}*\frac{1}{4}*\frac{1}{20}=\frac{7}{10*4}+\frac{7}{10*4*20}=\frac{7}{40}+\frac{7}{800}=\frac{140}{800}+\frac{7}{800}=\frac{147}{800}$. The complement of this would be $1-\frac{147}{800}$ or $\frac{653}{800}$. The final thing we can do is to make sure it is simplified and add the numerator and the denominator which is $653$ and $800$ so $653+800=1453$ This should be final answer. (Mathdash rating 800)

For the very hard question, What is the probability that the Squirtle will win this fight? (This is going to be a very long arithmetic series with a lot of cases. The max amount of turns this fight can have is 11 turns.)
This post has been edited 6 times. Last edited by PikaVee, Jun 1, 2025, 2:27 PM
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
iwastedmyusername
222 posts
#2 • 1 Y
Y by GA34-261
nah, i'd win
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
PikaVee
22 posts
#3
Y by
dang that person really won
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
PikaVee
22 posts
#4
Y by
I really need to solve this myself looking at that
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
NeoAzure
21 posts
#5
Y by
Comments:

Improve wording to make the end goal clear
Specify in the problem that you're only considering the chances of a pokemon fainting in one turn
Try to keep the problem on point while integrating a theme (consider mentioning that a squirtle dies in one hit of any attack to make it clear that thunder will make it faint) (try to limit the info thats not really necessary such as weakness and levels, or keep most of it but improve wording)

Solution is the same approach as yours, calculating hit chance by multiplying hit probability and not-blocked probability 7/10 x 3/4 = 21/40 then subtracting from 1 to get probability of blocking: 1 - 21/40 = 19/40.

Can also be solved by considering 2 cases where attack misses or hits but is blocked:
3/10 + 7/10 x 1/4 = 19/40
leading to the same answer. But efficiency is questionable.
This post has been edited 1 time. Last edited by NeoAzure, Jun 1, 2025, 5:18 AM
Reason: More details
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
PikaVee
22 posts
#6
Y by
Thanks, I'm going to edit it right now.
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
PikaVee
22 posts
#7
Y by
I will make the lives of the next person that solves the revised edition hell
Z K Y
The post below has been deleted. Click to close.
This post has been deleted. Click here to see post.
PikaVee
22 posts
#8
Y by
oh wait im going to modify it to its original question cause i almost forgot to put it
Z K Y
N Quick Reply
G
H
=
a