Announcements regarding our community
New editor released!

We've heard many requests to make it even easier to create rich content. It's always been our goal to create a system which empowers everyone with a vision of an interactive lesson to turn it into reality - without needing to know how to program. :)

Our first version, eML, helped to reduce the barrier significantly, but today, we've released an even easier-to-use lesson editor! It's still under intense development, and so you'll see it grow through leaps and bounds over the next few days. Give it a spin, and share your feedback! We'd be happy to improve it to the liking of our community. :)

read more
Girls on expii!

Attention all females of the expii community! Po-Shen Loh and I started a Facebook page for all the girls on expii so that we can boost the number of girls on this site (and hopefully in the world of mathematics in general) and inspire other young girls to be interested in math as well! If you're interested in joining, please find us on Facebook and we'll add you to the page!

read more
Let's build Algebra 1 and 2! Discuss content creation here.
Distributive Property

@Benjamin We have the distributive property here: (if you search "distributive property" this is the first result).

It's possible that it's missing somewhere else though---were you looking for it somewhere else? Let us know.

read more
What is the point of Maths?

You need math to program video games.

read more
Let's build Astronomy! Discuss content creation here.
Astronomy Edit-a-Thon, 2015 October 22 16:00 Pacific / 19:00 Eastern Time

Hi Michael! When is the next astronomy edit-a-thon? :)

read more
Let's build Biology! Discuss content creation here.
Let's build Calculus! Discuss content creation here.
Expii as part of a Calculus II class

Got it - thanks @CassieTaylor !

read more
Specific useful substitutions article

@Moor-Xu There's also a (Summary: How to Compute Integrals) topic now.

read more
Let's build Chemistry! Discuss content creation here.
Let's build Earth Science! Discuss content creation here.
Let's build Electricity and Magnetism! Discuss content creation here.

@Michael-Busch Thanks a lot for the response; makes sense!

read more
Let's build Geometry! Discuss content creation here.
Constructible Numbers?

Hi everyone!

I'm new to expii, and I've only just started to explore all the content here. I noticed that there isn't yet a topic on constructible numbers; will that be coming in the future? I think I have some writing that could contribute to that topic.

read more
Weekly Global Jam Sat Feb 21: Constructions (11am Eastern / 9:30pm India / 5pm Central Europe)

OK, I've posted an explanation here:

Feedback is welcome!

read more
Let's build Mechanics! Discuss content creation here.
Expii Jam on Wed Feb 25 at 9pm Eastern: Waves

Hi! Since @Po-Shen-Loh is currently on a plane to Munich en route to the Romanian Masters in Mathematics (wish team USA luck!), I'll be running this Jam today. Here's just some links to the pages about Waves that people can post in.

Since all these links have at most 1 post and no exercises, any contribution is very very helpful! Feel free to ask any questions, discuss any ideas, write/edit articles, etc. I'll be writing about interference in the meantime.

read more
Expii Jam Wed Jan 28 at 9pm Eastern: Energy

Thanks @Harrison-Grodin for coming today! You can continue, but I think that I'm done writing for the day. Thanks for a good Jam! I'll keep this page open in case you have questions or comments.

read more
Let's build Thermodynamics! Discuss content creation here.
General talk about math
USA TSTST 2015 solutions


Does anyone have the solutions for the USA TSTST 2015, especially problems 3 and 6, since there are no correct solutions posted on AoPS as of now?

read more

We're sponsoring ARML this weekend! Visit our table for free expii t-shirts! :) We'll be at the Penn State site, near the song contest area. It's our pleasure to support the enthusiast community, from which we trace our own roots!

read more
General talk about non-math
Happy New Year!

Our New Year Present for everyone is the launch of Astronomy! :)

read more
Expii Revolution begun even on Quora

Click here to share knowledge and ask questions about Expii on Quora. Lot of people are waiting staff and knowledgable users to share about Expii on Quora.Hope you guys turn there.

read more
Trying to figure out how to use the site?
How do I delete a post?

@Po-Shen-Loh Can I get deleted too, please? I accidentally typed this when I meant to type it in another tab, and saved it.

read more
Where is the Latex Tutorial?

I have used the Latex tutorial on AoPS.

read more
Got a feature request you'd like to see? Give us a shout here.
Profile Pictures for main site accounts?

Hi Qinzhuo,

We pull profile images from gravatar. So if you add an image to the email you use for Expii, we'll pull it down.


read more
Next Topic Button seems to be gone?

I remember a long time ago, there used to be a next topic button at the bottom of each page. I thought it seemed to be particularly useful. Can anyone tell me what happened to it?

read more
Having trouble with Expii? Let us know...
A few bug-reports about some Expii Solve problems

That was recently added- the first draft of the problem did not have the log languange in there. Thank you Expii for adding this. (Although the problem STILL doesn't take Log[2^150-1]- instead it appears to accept everything within [723,756] which is an interval of diameter 33 centered at about Log[148^148] for some insane reason. I'd love for someone to come up with a solution showing this and refuting the solutions proposed by Circonflexe and me.)

Edit 10/14: I figured it out with the help of someone who knows more graph theory than I do. It turns out that a random r-regular graph is almost surely r-connected- see here for claim. If you draw a 3-regular graph, you can pretty quickly find one that's big enough to do better than the cube.

read more
Can't edit solution to Expii Solve problem

@Jacob-Zhang Thanks for reporting this! We're on it right now! :) @Daniel-Liu also messaged me about this. We really appreciate having such a responsive community!

read more
Share pointers to learning resources
Practice Resources

The books are fine if you get the PDF version of it and print it yourself.

read more
Applied Mathematics Book

same place

You mean Caltech?

By the way, someone suggested that all books should have this warning

read more
News from around the world
The Improving Mathematics Education in Schools (TIMES) Project

Check these out! So many hidden gems in this world (the internet in particular). :) We'll definitely be consulting this for the upcoming Algebra map (which might include number theory and some counting as well)!

read more
The Algebra Project

Maybe this isn't news, but it is sort of for me. Have any of you heard of the Algebra Project before? I think it would be very interesting to connect with them at some point, although we would probably need to build an Algebra map (and establish a larger community) first. :)

read more