mohs of each oly

by cowstalker, Mar 23, 2025, 1:20 AM

what are the general concencus for the mohs of each of the problems on usajmo and usamo

funny title placeholder

by pikapika007, Mar 21, 2025, 12:10 PM

Let $S$ be a set of integers with the following properties:
  • $\{ 1, 2, \dots, 2025 \} \subseteq S$.
  • If $a, b \in S$ and $\gcd(a, b) = 1$, then $ab \in S$.
  • If for some $s \in S$, $s + 1$ is composite, then all positive divisors of $s + 1$ are in $S$.
Prove that $S$ contains all positive integers.
This post has been edited 1 time. Last edited by pikapika007, Mar 21, 2025, 12:12 PM
Reason: wrong year

usamOOK geometry

by KevinYang2.71, Mar 21, 2025, 12:00 PM

Let $H$ be the orthocenter of acute triangle $ABC$, let $F$ be the foot of the altitude from $C$ to $AB$, and let $P$ be the reflection of $H$ across $BC$. Suppose that the circumcircle of triangle $AFP$ intersects line $BC$ at two distinct points $X$ and $Y$. Prove that $C$ is the midpoint of $XY$.

Distributing cupcakes

by KevinYang2.71, Mar 21, 2025, 12:00 PM

Let $m$ and $n$ be positive integers with $m\geq n$. There are $m$ cupcakes of different flavors arranged around a circle and $n$ people who like cupcakes. Each person assigns a nonnegative real number score to each cupcake, depending on how much they like the cupcake. Suppose that for each person $P$, it is possible to partition the circle of $m$ cupcakes into $n$ groups of consecutive cupcakes so that the sum of $P$'s scores of the cupcakes in each group is at least $1$. Prove that it is possible to distribute the $m$ cupcakes to the $n$ people so that each person $P$ receives cupcakes of total score at least $1$ with respect to $P$.

combo j3 :blobheart:

by rhydon516, Mar 20, 2025, 12:08 PM

Let $m$ and $n$ be positive integers, and let $\mathcal R$ be a $2m\times 2n$ grid of unit squares.

A domino is a $1\times2$ or $2\times1$ rectangle. A subset $S$ of grid squares in $\mathcal R$ is domino-tileable if dominoes can be placed to cover every square of $S$ exactly once with no domino extending outside of $S$. Note: The empty set is domino tileable.

An up-right path is a path from the lower-left corner of $\mathcal R$ to the upper-right corner of $\mathcal R$ formed by exactly $2m+2n$ edges of the grid squares.

Determine, with proof, in terms of $m$ and $n$, the number of up-right paths that divide $\mathcal R$ into two domino-tileable subsets.
This post has been edited 1 time. Last edited by rhydon516, Mar 20, 2025, 12:09 PM

Base 2n of n^k

by KevinYang2.71, Mar 20, 2025, 12:01 PM

Let $k$ and $d$ be positive integers. Prove that there exists a positive integer $N$ such that for every odd integer $n>N$, the digits in the base-$2n$ representation of $n^k$ are all greater than $d$.

Gunn Math Competition

by the_math_prodigy, Mar 8, 2025, 8:13 PM

Gunn Math Circle is excited to host the fourth annual Gunn Math Competition (GMC)! GMC will take place at Gunn High School in Palo Alto, California on Sunday, March 30th. Gather a team of up to four and compete for over $7,500 in prizes! The contest features three rounds: Individual, Guts, and Team. We welcome participants of all skill levels, with separate Beginner and Advanced divisions for all students.

Registration is free and now open at compete.gunnmathcircle.org. The deadline to sign up is March 27th.

Special Guest Speaker: Po-Shen Loh!!!
We are honored to welcome Po-Shen Loh, a world-renowned mathematician, Carnegie Mellon professor, and former coach of the USA International Math Olympiad team. He will deliver a 30-minute talk to both students and parents, offering deep insights into mathematical thinking and problem-solving in the age of AI!

View competition manual, schedule, prize pool at compete.gunnmathcircle.org . For any questions, reach out at ghsmathcircle@gmail.com or ask in Discord.
Attachments:
This post has been edited 7 times. Last edited by AoPSSheriff, Mar 18, 2025, 4:24 PM
Reason: Removed discord link.

Portia's vs. Lara's school

by MathArt4, Feb 5, 2021, 5:47 PM

Portia’s high school has $3$ times as many students as Lara’s high school. The two high schools have a total of
$2600$ students. How many students does Portia’s high school have?

$\textbf{(A) }600 \qquad \textbf{(B) }650 \qquad \textbf{(C) }1950 \qquad \textbf{(D) }2000 \qquad \textbf{(E) }2050$
This post has been edited 4 times. Last edited by nsato, Dec 30, 2021, 8:19 PM

2021 AMC10A Problem 1

by Professor-Mom, Feb 5, 2021, 5:38 PM

Triangle in a square

by fortenforge, Feb 6, 2013, 5:41 PM

Square $ ABCD $ has side length $ 10 $. Point $ E $ is on $ \overline{BC} $, and the area of $ \bigtriangleup ABE $ is $ 40 $. What is $ BE $?

$\textbf{(A)} \ 4 \qquad \textbf{(B)} \ 5 \qquad \textbf{(C)} \ 6 \qquad \textbf{(D)} \ 7 \qquad \textbf{(E)} \ 8 \qquad $

[asy]
pair A,B,C,D,E;
A=(0,0);
B=(0,50);
C=(50,50);
D=(50,0);
E = (30,50);
   draw(A--B);
   draw(B--E);
   draw(E--C);
draw(C--D);
draw(D--A);
draw(A--E);
dot(A);
dot(B);
dot(C);
dot(D);
dot(E);
label("A",A,SW);
label("B",B,NW);
label("C",C,NE);
label("D",D,SE);
label("E",E,N);

[/asy]
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  • !!!!!!!!

    by stroller, Mar 10, 2020, 8:15 PM

  • cooooooool
    nice blog

    by Navansh, Jun 4, 2019, 7:47 AM

  • Victor is one of the GOATs.

    by awesomemathlete, Oct 2, 2018, 11:48 PM

  • This blog is truly amazing.

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  • what a gem.

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    by ahaanomegas, Dec 15, 2013, 7:21 PM

  • yo dawg i heard you imo

    by Mewto55555, Aug 1, 2013, 10:25 PM

  • Good job on 5 problems on USAMO. I know that is a pretty bad score for someone as awesome as you on a normal USAMO, but no one got all 6 this year so it's GREAT!

    VICTOR WANG 42 ON IMO 2013 LET'S GO.

    See you at MOP this year (probably :) ).

    by yugrey, May 3, 2013, 10:32 PM

  • you can just write "Solution

    by math154, Feb 6, 2013, 6:33 PM

  • Hello. May I ask a stupid question: how to turn "Hidden Text" into hidden "Solution" tag?

    by ysymyth, Feb 1, 2013, 12:59 PM

  • This is a good blog.I like it.

    by Lingqiao, Jul 17, 2012, 4:21 PM

  • hi.i like the blog.

    by Dranzer, Feb 9, 2012, 12:25 PM

  • sorry, i've decided this blog is just for the random stuff i do. don't take it personally... you can always post things on your own blog

    by math154, Nov 23, 2011, 10:26 PM

  • what i got uncontribbed for posting a nice geo problem?

    by yugrey, Nov 23, 2011, 1:32 AM

  • Can I be a contributor?

    by Binomial-theorem, Oct 5, 2011, 12:39 AM

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