## 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?

Here's a fun circle squaring limerick, reprinted at the Division by Zero blog:

Said the man about town, ‘I have a flair

For squaring the circle, I swear.’

But he found that the strain

Was too great for his brain,

So he’s gone back to circling the square.

Kate at f(t) brings to our attention the very fun "Here Come the 123s Nonagons" video! Catchy music too!

Here's a great find by Mr. Chase: Funny Little Calculus Text. Not your typical Calculus text. Do check it out!

The Mathematical Tourist blog has an amazing Mobius strip construction from a letter that Martin Gardner wrote to Ivars Peterson, blog author and Director of Publications and Communications at the Mathematical Association of America.

Martin concluded with the following instructions: "Trisect the twisted band, then bisect the untwisted one, and open up for a big surprise!"

I'll leave you with an unsolved problem from Fun with Num3ers:

One of the unsolved problems in mathematics. A number theory question:

Does there exist a rectangular box all of whose edges and diagonals are integers?

A rectangular box is a solid with six rectangular faces.

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