Tag: math

If I don’t finish reading Othello today, this puzzle is why. Since I love passing on methods of procrastination to you, here you go. Even though it’s a math puzzle, the most advanced math you need to solve it is knowledge of divisibility rules, which aren’t too advanced.

Here’s your puzzle:

Arrange the digits 1-9 such that the number formed by the first n digits in order is divisible by n.

That is, the first digit is divisible by 1, the number formed by the first two digits is divisible by 2, and so on. You should be able to figure out the place of one of the digits very quickly. The rest will take a bit more work.

Have fun!

You know about Chuck Norris facts if you’ve been on the Internet long enough. If you’ve done NaNoWriMo and you run in certain circles, you probably also know about Mattkinsi facts and that you should #lickmattkinsi to improve everything in your life.

But you might not know about Gauss facts, and that’s a crying shame. Carl Freidrich Gauss was one of those genius mathematicians who left no area of math untouched during his lifetime, and mathematicians today know it. You probably know it too, even if your math education ends at high school. Did you ever learn how to take the sum of n consecutive numbers? Your teacher might have told you a story about a mathematician who figured it out, probably involving a brutish schoolteacher who wanted to keep the kids busy only to find out that one kid figured out the solution instantly. That mathematician was probably Gauss, but whether he really did that is debated. There’s also an entire Wikipedia list of things named after Gauss.

With all that in mind, there’s definitely a good reason for Gauss to have his facts. These facts are hilarious and nerdy, as you’d expect. I laughed out loud while reading them since I understood almost all of them. The gist is the same as Chuck Norris facts (or any facts of these nature, really). Some of them are funny because they’re not possible in our world, mathematical or not. Others are funny because Gauss is suddenly the supermathematician from above that some have thought of him as. Others… aw, why am I explaining the joke? Go read some of them. Laugh. Look up a couple of the ones you don’t get. Learn something.

Hitler learns topology and explains one of the things that always confused me when I learned about open and closed sets. I’m with Hitler on this one. Open and closed sets? Neither open nor closed? It’s enough to make your head hurt if you think about it too hard. Too bad Downfall parodies weren’t a big thing when I was taking real analysis, or my professor would have heard references to this video every day (in a joking way, of course).

A friend asked me via Twitter what I thought of this io9 article about why pi was wrong. That’s right, pi: the circumference of a circle divided by its diameter. In Euclidean geometry that’s equal to approximately 3.1415926535897… and is irrational. The person io9 interviewed for the article is a proponent for a new constant called tau (after the Greek letter) that is the circumference divided by the radius. In other words, a constant for twice pi.

There’s a website promoting the correctness of tau as the correct value, claiming pi to be wrong just as the article does. The website isn’t not talking about the mathematical incorrectness of pi, but the site and io9 are using headline trickery to pull readers in.

The Tau Manifesto is disappointing. All it shows is that the choice of pi vs. tau is arbitrary at best, and we as a society chose pi over history because pi was discovered first. Besides, writing 2*pi is nicer than tau/2. This tau movement isn’t going to catch on. It’s not even on Wikipedia!

It’s no secret that I’m a huge geek, but spending the better part of an evening reading an abstract algebra book may seal the deal. I started by comparing the two books that I learned algebra from. The first book was a book written by my professor just for the class; the second was a dense and well-known algebra book (Dummit and Foote’s Abstract Algebra, if you’re really curious) and the book I used for my special study in algebra. I knew there would be a lot of differences just because of the natures of the two books. One book contained humor; the other did not. One book left more exercises for the reader than the other. One book has a downright awful definition for a quotient group. Well, once you read all the context behind the definition it’s a little less awful, but the definition can really be condensed into much easier terms. Really, Dummit and Foote, you don’t need to use fibers to explain a quotient group.

I’ve had a lot of fun this evening going through my algebra books, though. If I weren’t pressured by the need to sleep I’d be staying up longer to keep reading and working on exercises. Yes, this is my Friday night: doing abstract algebra for fun. That’s what the weekend is for, though.