## Wild About Math bloggers 11/19/10

[ The latest roundup is at Equalis. Here's last week's edition. ]

Fun happenings this week in the blogosphere.

I'm excited to discover that Sue from Math Mam Writes... interviewed James Tanton. I missed the interview but a recording is here. Mr. Tanton is a very talented mathematician, Math teacher, author of fantastic Math books.

Can bacteria solve sudoku puzzles? Sort of. Check out this New Scientist article.

From Math Less Traveled:

What happens when you hook up three projectors to a single video camera, and then point the camera at the projected images?

RIDICULOUSLY AWESOME THINGS, that’s what!

Mathematica 8 has been announced.

But probably the single greatest—and most surprising—new capability of Mathematica 8 is one that cuts across all areas: the integration of Wolfram|Alpha into Mathematica, and the notion of free-form linguistic input.

Alex Bellos introduces us to solids of constant width beyond the obvious sphere.

If you ever wanted to prove Euler's Formula (V-E+F=2 for any convex polyhedron) check out this article at the Geometry Junkyard. Hat tip to Ars Mathematica.

Maria at Math Accent reviews a book, Sliceforms. It's a twist of sorts on Origami.

Finally, I'll leave you with a puzzle. Fun with Num3ers has an intriguing puzzle:

If we take the numbers from 1 to 15 (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15) and rearrange them in such an order that any two consecutive numbers in the sequence add up to a perfect square, we get,

8 1 15 10 6 3 13 12 4 5 11 14 2 7 9 9 16 25 16 9 16 25 16 9 16 25 16 9 16ask the readers the following:

Can you take the numbers from 1 to 25 to produce such an arrangement?

How about the numbers from 1 to 100?

## Wild About Math bloggers 11/12/10

[ Here's a link to last Friday's Equalis post. ]

Here are some fun findings from the blogosphere:

The latest Carnival of Mathematics has been posted. I've not had time to review it.

Thanks to Shecky, I read "Large cardinals: maths shaken by the 'unprovable' ," which is a disturbing look at the foundation of mathematics:

In the esoteric world of mathematical logic, a dramatic discovery has been made. Previously unnoticed gaps have been found at the very heart of maths. What is more, the only way to repair these holes is with monstrous, mysterious infinities.

Alex Bellos has a fun article on his blog, Cubism 2010, about the resurgence of interest in Rubik's cube. There's a lot of fun cube trivia in this article. And, I learned that there's a 7x7x7 cube.

Dave at Division by Zero has discovered that Google Translate now knows Latin. That's pretty exciting for anyone wanting to read ancient mathematical texts.

## TI-84 calculator giveaway winner

[ Sorry for the delay in announcing the winner. I ran into a technical issue that I needed to get resolved.]

On November 1st I announced a contest. Folks entering the contest were eligible to win if they correctly solved a Math problem of my choosing. The prize was a TI-84 calculator, graciously donated by Texas Instruments.

Random.org selected Nate Burchell as our winner. We had 20 submissions. Almost all of them were correct.

I sometimes post a solution other than the winner's because sometimes the winner's solution, while correct and well explained, is not the best example of how to solve a problem. In this case, though, Nate explained his solution quite well.

Here is Nate's solution.

Nate is a Math teacher and blogs at http://burchellmath.blogspot.com.

Thanks to everyone who played. Stay tuned for another puzzle or three in the coming weeks.

## Wild About Math bloggers 11/5/10

[ Today's Equalis post is up. Here's last week's. ]

Welcome, everyone! Here's a small piece of action in the blogosphere this past week.

Texas Instruments is giving away a TI-84 Plus Silver Edition calculator at my Wild About Math! blog. You've got to solve a problem to be eligible to win and you've got to hurry as the contest ends very soon.

Denise at Let's Play Math tells us about a great sale at Lulu -- $20 off an order of $20 or more. Wow! Sale in the US only and through 11/30.

If you ever wanted six different proofs that the harmonic series diverges look no further than CTK Insights. Proof 5 is my favorite. Which is yours?

## Great sale at Lulu

Thanks to Denise at Let's Play Math I learned about this great sale at Lulu. Take $20 off any order of $20 or more. Valid through 11/30/10 in the US only. Wow! Many books are print-on-demand and you'll have to pay for shipping. But some, like this one from my hero James Tanton, are free with the coupon.

## Review: Monkey Pod Games

Who doesn't like puzzles? I remember playing with devious barrel-shaped wooden puzzles as a kid. I was recently contacted by Rachel at Monkey Pod Games asking if I'd be willing to review one of their puzzles. I always take a look at a company's web-site before I agree to a review as I've discovered that free stuff isn't free since I have to spend time reading a book or playing with a puzzle or game. If I don't like what I see or if I think a product is too expensive to appeal to readers then I won't take a review copy.

I liked what I saw at the Monkey Pod Games site so I humbly agreed to accept a "The Perplexing X in a Box" puzzle. I received it a few days later. It's a devious little puzzle. I couldn't figure it out and I ended up going to the Monkey Pod web-site to get the solution.

## Wild About Math bloggers 10/29/10

[ This week's Wild About Math bloggers post is up at Equalis. Here is last week's article. ]

Lots happening in the Math blogosphere this week. Here's a sampling:

Here's a timely article about baseball and Math. Winning the World Series with math: A nearly circular path could be the fastest way to home plate gives a counter-intuitive approach to running around the bases. Hat tip to Maria.

Denise at Let's Play Math posts a YouTube video by James Tanton about a great paradox -- how a figure can have finite area but infinite length. (Yes, my Math is really sloppy here.)

(Shecky points out in Mandelbrot, Mobius, Mirth that the Koch Snowflake also has this property.) I notice that James Tanton has uploaded 85 videos to YouTube. Another nice one is Egyptian Fractions and Fibonacci's Greedy Algorithm. Check out James Tanton's web-site for great videos and essays. I love this man's philosophy. He has articulated very well what my relationship with Math has always been.

## An incredible magic square

From Grey Matters:

In the following video from Germany, performer Robin Wersig asks for a 3-digit number, getting 843 as a reply, and then asks for a starting square, for which D2 is given. He then proceeds to start at square D2, and creates an 8 by 8 magic square totaling 843 in every row and column, all while performing a Knight's Tour!

## TI-84 Plus Silver Edition giveaway puzzle contest

**The contest is over. I've announced the winner here.**

[ Update 11/2. I changed the title of the post to say "TI-84 Plus Silver Edition" rather than "TI-Nspire." ]

No, I'm not reviving Monday Math Madness on a regular basis but Texas Instruments (TI) has offered calculators and t-shirts to readers so I'm going to run a few puzzle contests and give away a prize to the winner of each contest.

Before I announce the contest and rules, here's a word from our sponsor:

STEM skills - science, technology engineering and math - hold the key to tomorrow's innovation. To help students learn tomorrow's job skills, Wild About Math! has teamed-up with Texas Instruments to give away a TI-84 Plus Silver Edition graphing calculator with GraphiTI package. To learn more about TI-84 graphing calculators or other TI products, visit: http://education.ti.com. To learn more about STEM careers, visit: http://education.ti.com/studentzone.