## Pi Day Music Video

Another fan letter, this one from Jimmy Pascascio of Music Notes Online. As regular readers know I rarely plug commercial math ventures. I'm making an exception here because I like what these folks are doing. And, it's a great fit for a Pi Day post. Enjoy!

Hello Sol,

I came across your blog and noticed that you recently posted a music video from the BYU Mathletes about Pi. I am a teacher in Los Angeles and, along with a couple colleagues, I have an educational music company that has created a series of math songs and videos. I thought I would pass along our own Pi music video for you to take a look at and possibly share. The link is youtu.be/vG8iARxjHxs Considering Pi Day is upon us, now seems like an appropriate time to have an extra serving of Pi! Keep up the great work on your blog.

## The BYU Mathletes

I recently got this email about the BYU Mathletes and I thought I'd share it. The rap video is great.

Sol,

I recently saw that you highlighted Matt Lane and pointed out that he has a blog that looks at the intersection between math and pop culture.

Recently at my school (BYU) we created a video that epitomizes this. We have some amazing mathletes at our school and we wanted to find a fun way to highlight their accomplishments, so we created a math rap video. Here it is- http://www.youtube.com/watch?v=0AGT4M3Z1OM and here is some more info on the mathletes- http://bit.ly/BYUmathletes I’m sure this is something that your readers and listeners would enjoy!

Best,

Matt Hopkins

Brigham Young University

## Matt Lane – Math Goes Pop!

I received this email yesterday from Matt Lane of Math Goes Pop! I really like what Matt is up to, exposing how Math is an integral (pun intended) part of popular culture. Matt is one of those Math geeks who is also an outstanding communicator - and he likes my blog - so, with his permission, I'm publishing his email.

Hey Sol,

My name is Matt Lane, I'm a PhD candidate in mathematics from UCLA, and am also the founder of Math Goes Pop! (www.mathgoespop.com), a blog that explores the (surprisingly rich) intersection between math and pop culture. Among other things, I've written about Futurama, Scott Pilgrim vs. the World, and Parks and Recreation. I also have a paper coming out in a forthcoming collection of essays on math and pop culture (see here). More info about me can be found on the Math Goes Pop website. I just became aware of your site through your Keith Devlin interview, and wanted to drop you a line and let you know that you can consider me one of your newest fans. I dig your work, so I thought I'd introduce myself. Here's to making cyberspace a little less lonely!

All the best,

Matt

## Plotting “traveling salesman problem” routes on an iPhone

Here's something quite remarkable, from the Princeton University Press Blog:

Twenty-four years ago a 2,392-city example of the TSP was solved in a 23-hour run on a super computer to set a new world record. This same problem now solves in 7 minutes on an iPhone 4 thanks to a free app: Concorde TSP Solver!

iTunes: http://itunes.apple.com/us/app/concorde-tsp/id498366515

Press release for Concorde TSP Solver: http://press.princeton.edu/blog/wp-content/uploads/2012/02/Cook-TSP-app.pdfBill Cook, author of In Pursuit of the Traveling Salesman, has just launched a FREE app in the iTunes store called CONCORDE TSP SOLVER. The app allows users to plot TSP routes for an uploaded list of cities or any number of random cities.

The CONCORDE TSP SOLVER app is a powerful display of the potential to solve on mobile devices large examples of even the most difficult computational problems. This makes it an ideal tool for understanding and teaching the mathematics behind the most successful line-of-attack on the salesman problem. The colorful graphics show step-by-step how a tool called linear programming zeros in on the optimal route to visit a displayed collection of cities.

CONCORDE TSP SOLVER is a great companion to Cook’s book In Pursuit of the Traveling Salesman for general readers and mathematics students alike.

I've received a review copy of the book from Princeton University Press but have not had a chance to read it yet. A couple of reviews are available at Amazon.com.

A table of contents and chapter one of the book are available at the publisher's website.

## From “God Plays Dice,” an interesting geometry problem

Here's a cute problem (from Robert M. Young, Excursions in Calculus, p. 244): "What is the average straight line distance between two points on a sphere of radius 1?"

(Answer to follow.)

Note the number of comments with different answers.

"Excursions in Calculus," from what I could see at Google Books, looks like it has many interesting problems.

## New math book makes its debut on Fibonacci Day

Today is 11/23, which some call Fibonacci Day. I received an email a few days ago from a Mr. Tony Gonzalez who has translated a very popular Japanese math book into English. I did receive a PDF review copy and liked what I saw but will wait to receive a printed copy before reading and reviewing. Here's Tony's email and press release. Tony, I wish you much success.

Hi, Sol.

My name is Tony Gonzalez. I'm a former math teacher (which is how I came to know your blog), but I'm now working mainly as a translator and publisher. I'm writing to let you know about a book that I translated and my company will be publishing next week, "Math Girls". We will be releasing the book on 11/23, "Fibonacci Day", perhaps making it a good topic for a blog post on that day?

I'm taking the liberty of sending you a press release announcing the publication (below). That should give you the rough details, but if you have any questions do please feel free to contact me by email, or you can get more information about the book at our website, bentobooks.com.

Thank you!

―Tony

_______________________________________

Press release

--- For immediate release ---

## Another clever exploration by James Tanton

I really enjoy James Tanton's Math explorations because they tend to be easy to describe and rich in exploration value. Here's such an exploration:

The problem statement is very simple. Is there a way in which we can say that there are more triangular numbers than square numbers? If so, how do we compare the sizes of the two sets? Can we compute the ratio of triangular to square numbers where both T(n) and S(n) are less than an arbitrary constant? Can we generalize what we find for other polygonal numbers?

This is a great exploration!

## A great triangle exploration

Mr. Honner has a great exploration at his blog. It starts with a simple question, that has subtlety and depth to it: How do you determine the "equilateralness" of a triangle? Can you compare two triangles and determine which is more equilateral than the other?

The post introducing the investigation is here. I encourage you to do your own exploring before reading the 28 comments which are rich in ideas. Once you've played around with the ideas yourself then take a look at what Mr. Honner came up with in Part II.

I love this kind of exploration for a number of reasons:

- The question is simple to understand.
- Just like in the real world there are multiple approaches.
- It's not clear that there is a right solution but some are better than others.
- Students get to think about properties of triangles in new and different ways.
- Students get to think deeply about the notion of "metric."
- This problem is more interesting than many other geometry problems I've seen.

Nice!

## Seeking interesting math factoids about the number 11

I'll be doing a brief talk at a conference next month, on 11/11/11 at 11:11AM, about the number 11. If you know interesting factoids about 11 (or about 1111...) that I could include in the talk I'd greatly appreciate it.

One factoid is that 1/(1+(1/(1+1/(1+... converges to the golden ratio.

Another is that if a number is divisible by 11, reversing its digits will result in another multiple of 11.

Other ideas?

Thanks.