Arithmetic

May is an exciting month! National MATHCOUNTS is the second week of May in Washington D.C. and our Founder, Richard Rusczyk will be presenting a seminar, Preparing Strong Math Students for College and Careers, on May 11th.

Are you interested in working towards MATHCOUNTS and don’t know where to start? We have you covered! If you have taken Prealgebra, then you are ready for MATHCOUNTS/AMC 8 Basics. Already aiming for State or National MATHCOUNTS and harder AMC 8 problems? Then our MATHCOUNTS/AMC 8 Advanced course is for you.

Summer camps are starting next month at the Virtual Campus in math and language arts that are 2 - to 4 - weeks in duration. Spaces are still available - don’t miss your chance to have an enriching summer experience. 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 upcoming events:
[list][*]May 9th, 4:30pm PT/7:30pm ET, Casework 2: Overwhelming Evidence — A Text Adventure, a game where participants will work together to navigate the map, solve puzzles, and win! All are welcome.
[*]May 19th, 4:30pm PT/7:30pm ET, What's Next After Beast Academy?, designed for students finishing Beast Academy and ready for Prealgebra 1.
[*]May 20th, 4:00pm PT/7:00pm ET, Mathcamp 2025 Qualifying Quiz Part 1 Math Jam, Problems 1 to 4, join the Canada/USA Mathcamp staff for this exciting Math Jam, where they discuss solutions to Problems 1 to 4 of the 2025 Mathcamp Qualifying Quiz!
[*]May 21st, 4:00pm PT/7:00pm ET, Mathcamp 2025 Qualifying Quiz Part 2 Math Jam, Problems 5 and 6, Canada/USA Mathcamp staff will discuss solutions to Problems 5 and 6 of the 2025 Mathcamp Qualifying Quiz![/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

May 1, 2025

0 replies

Interesting question from Al-Khwarezmi olympiad 2024 P3, day1

Adventure1000 1

N 7 minutes ago by pooh123

Find all $x, y, z \in \left (0, \frac{1}{2}\right )$ such that
$\begin{cases} (3 x^{2}+y^{2}) \sqrt{1-4 z^{2}} \geq z; \\ (3 y^{2}+z^{2}) \sqrt{1-4 x^{2}} \geq x; \\ (3 z^{2}+x^{2}) \sqrt{1-4 y^{2}} \geq y. \end{cases}$ Proposed by Ngo Van Trang, Vietnam

1 reply

Adventure1000

Yesterday at 4:10 PM

pooh123

7 minutes ago

one nice!

MihaiT 3

N 23 minutes ago by Pin123

Find positiv integer numbers $(a,b)$ s.t. $\frac{a}{b-2}$ and $\frac{3b-6}{a-3}$ be positiv integer numbers.

3 replies

MihaiT

Jan 14, 2025

Pin123

23 minutes ago

Acute Angle Altitudes... say that ten times fast

Math-lover1 1

N an hour ago by pooh123

In acute triangle $ABC$ , points $D$ and $E$ are the feet of the angle bisector and altitude from $A$ , respectively. Suppose that $AC-AB=36$ and $DC-DB=24$ . Compute $EC-EB$ .

1 reply

Math-lover1

Yesterday at 11:30 PM

pooh123

an hour ago

Find a and b such that a^2 = (a-b)^3 + b and a and b are coprimes

picysm 2

N 5 hours ago by picysm

it is given that a and b are coprime to each other and a, b belong to N*

2 replies

picysm

Apr 25, 2025

picysm

5 hours ago

Computer Science

rrusczyk 0

Nov 10, 2009

I've frequently ranted about how much easier it was for people in my generation to get started with programming than it is for students now. This post that levans pointed me to not only gives a vivid example, but also explains that making it harder for kids to get started with computing puts restrictions on their educational development in other areas, too. One of these days . . . .

0 replies

rrusczyk

Nov 10, 2009

0 replies

Master the Hard Stuff: CS Edition

rrusczyk 6

N Aug 19, 2009 by pascal_1588

Just last night I was recalling (not fondly) the days of malloc and calloc and worrying about memory when coding in C. Then today, a parent pointed me at this article, which gives, I think, a pretty good defense of why it was a good thing for me to have to deal with. I think there's something to his argument that is a lot like the argument I make when I argue that rapid acceleration within mathematics to fancier and fancier tools is not the best route for a gifted young student to take.

6 replies

rrusczyk

Aug 15, 2009

pascal_1588

Aug 19, 2009

Project Euler

rrusczyk 7

N Aug 18, 2009 by jhangil

Do any of you have experience with Project Euler? If so, what do you think?

7 replies

rrusczyk

Aug 13, 2009

jhangil

Aug 18, 2009

No more topics!

Arithmetic

Rounak_iitr 3

N Apr 12, 2025 by evt917

p2. In a room of $20$ people, $65\%$ are wearing a jacket and $40\%$ are wearing a hat. If $4$ people are wearing neither, how many people are wearing both $?$

3 replies

Rounak_iitr

Dec 4, 2023

evt917

Apr 12, 2025

Arithmetic

G H J

Reveal topic tags

arithmetic

G H BBookmark kLocked kLocked NReply

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Rounak_iitr

456 posts

Rounak_iitr

#1 h Dec 4, 2023, 4:15 PM

Y by

p2. In a room of $20$ people, $65\%$ are wearing a jacket and $40\%$ are wearing a hat. If $4$ people are wearing neither, how many people are wearing both $?$

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MC413551

2228 posts

MC413551

#2 h Dec 4, 2023, 5:56 PM

Y by

13 have a jacket and 8 have a hat and 4 have neither so 20-4=16 and 13+8-x=16 so there are 5 people wearing both

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imnotgoodatmathsorry

80 posts

imnotgoodatmathsorry

#3 h Apr 12, 2025, 1:52 AM

Y by

Rounak_iitr wrote:

p2. In a room of $20$ people, $65\%$ are wearing a jacket and $40\%$ are wearing a hat. If $4$ people are wearing neither, how many people are wearing both $?$

THIS IS VENN DIAGRAM!
There are $13$ peoples who wears jacket and $8$ peoples who wears hat is $16$ people (That are wearing each one of two or both)
So, there will be $(13+8)-16=5$ people that are wearing both

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evt917

2410 posts

evt917

#4 h Apr 12, 2025, 1:57 AM

Y by

nahh how is this hsm

this should be in msm

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