## Wild About Math bloggers 3/4/11

Welcome to Spring, at least here in Santa Fe, where it's 60 degrees! Just a few weeks ago it dipped to -10 degrees here. Onto Math ...

James Tanton has a really great, very accessible, four part introduction to the Partition Numbers and to the hunt for structure in these numbers. Here's the first video:

Patrick at Math jokes 4 mathy folks has a great puzzle:

Append the digit 1 to the end of every triangular number. For instance, from 3 you’d get 31, and from 666 you’d get 6,661. Now take a look at all of the divisors of the numbers you’ve created. What are the units digits of the divisors for every number created in this way? Can you prove that this result always holds?

Hat tip to Brent.

Jonathan Stokes has an interesting article. He explores what happens when one maps algebraic chess notation to scientific pitch notation.

Hat tip to Maria Miller.

Dan at math4love writes (briefly) about a book he's discovered, Family Math. Judging from the reviews at Amazon the book should be really good and used copies are available very inexpensively.

The Grey Matters Blog has a number of embedded videos that show arithmetic tricks. Here's a particularly nice trick that's new to me:

+plus magazine has a nice two-part series: 101 uses of a quadratic equation.

Hat tip to Ben Vitale.

Here's a nice but useless piece of trivia, courtesy of Futility Closet:

9999999999999999999999999999999999999999

9999999999999999999999999999999999999999

9999999999999999999999999999999999999999

9999999999999999999999999999999999999999

9999999999999999999999999999999999999999

9999999999999999999999999999999999999999

9999999999998999999999999999999999999999

9999999999999999999999999999999999999999

9999999999999999999999999999999999999999

9999999999999999999999999999999999999999

9999999999999999999999999999999999999999

9999999999999999999999999999999999999999

99999999999999999999999999 is prime.

Look closely at the number before you object!

I'll end this edition with a cute cartoon from xkcd.

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