## A fun moving cube kids can make

Here's a great craft project for kids to make using wooden cubes and duct tape. An adult will need to help with the cutting of the image to place on the cubes. I think it would be extra fun to design two images that work in such a way that you see one or the other depending on which way the cubes turn.

Hat tip to Richard Wiseman.

## Can you name … ?

## Can You Name All 16 Non-Negative Integers Whose English Names Spell With No Repeating Letters In 10 Minutes?

While there are an infinite amount of numbers, there are, surprisingly, only 16 different non-negative integers (in other words, whole numbers greater than -1) whose names in English, when spelled out, have no repeating letters.

For example, 7 doesn't fit, because when spelled out as S-E-V-E-N, the word has two Es. -2 might seem to work, as it is spelled M-I-N-U-S-T-W-O, and has no repeating letters, but it doesn't qualify because it's negative, and I specified non-negative integers.

Enter as many of these numbers, but you must enter your answers as digits, not spelled out. This keeps spelling from being an issue. If you enter a number greater than 999, you can enter the number with or without commas.

Take the quiz and see how you do.

## Send fractional congresspersons to the Capitol

George Szpiro, author of "Numbers Rule: The Vexing Mathematics of Democracy, from Plato to the Present" is a mathematician and journalist. Szpiro has an interesting op-ed piece in which he offers a brief history of the mathematical paradoxes of apportionment and then argues for an innovative solution: “send fractional congresspersons to the Capitol.”

Sounds impossible, but Szpiro uses Math to show how it might work.

## 12 cent Math trick

Here's a very interesting and simple trick to impress your friends. It's simple enough to do that even the little ones, if they can count to 12, can do this trick. There's no sleight of hand or any other difficult manipulation to do. In fact, once you know the very simple steps, the trick is pretty automatic.

The trick is based on some very simple algebra but I've found that even though I understand how the trick works it's still eerie to see it work.

I got this trick from Shecky's great Math-Frolic Blog. The trick was developed by Alfred Posamentier, a prolific writer of Math books. While Posamentier is not as well known as Martin Gardner or Cliff Pickover, his books are equally engaging.

I rewrote Posamentier's trick so that it could be performed as a bar trick so that maybe Scam School will pick up the idea and produce a video of it.

Here's my version of the trick:

The scamster hands the victim 12 pennies and then blindfolds himself. The victim is instructed to place the coins on the table such that exactly five of them are heads up. The scamster tells the victim that he can, without removing the blindfold, separate the 12 pennies into two groups, and turn over some pennies so that each group will have exactly the same number of coins heads up. Fumbling around because he can't see, the scamster moves the 12 pennies close together into a group and then somehow picks some of the pennies and moves them to another group. He then turns some coins over and, voila, both groups have the same number of heads up pennies.

How can the scamster know how to separate the coins into two piles? How does he know which coins to turn over? How can he do this all blind-folded? See if you can figure out the trick on your own then head on over to Shecky's blog for Posamentier's solution.

## Challenging probability SAT Math problem

Can you solve this not-so-easy probability problem?

Do you know of other challenging problems?

## Fractal video fun

Check out this great music video! The animation is great and the music absolutely rocks. I watched this thing a whole bunch of times just for the music.

## Carnival of Mathematics and Multimedia #1

Guillermo Bautista has launched the latest Math Carnival. The Carnival of Mathematics and Multimedia is hosted at Guillermo's Blog of the same name.

Carnival #1 has 23 entries, a very respectable number for a new (and even for a not so new) carnival.

Guillermo will be nurturing the new baby carnival at his site for a couple of months but is then open having it become a traveling carnival. Guillermo - I'll be happy to host one.

The carnival emphasizes the following kinds of articles:

- connections between and among different topics in mathematics as well connection of mathematics to other fields
- use of mathematics in solving real life problems
- clear, non-bookish conceptual explanations of mathematical concepts, particularly those which are hard to teach and difficult to learn
- integration of technology in teaching mathematics
- introduction of new software and Web 2.0 technologies
- software reviews and tutorials

[ Photo: Over the Fair by Lyn Columbe ]

## “When will I use this?”

Mathalicious is a great Math resource that illustrates the very practical use of Math in real world situations. The scenarios make for great classroom or homeschool explorations.

Here are some of the topics covered:

The Biggest Loser?

What is the math of weight loss? If two people each lose 100 pounds, is that necessarily the same thing? In this lesson, we’ll use percents to explore the mathematics behind the popular game show.

Cell Phone Extravaganza

Do you have a cell phone plan? If so, do you have the right plan? In this lesson, we’ll explore the algebra behind voice and text message plans, and will figure out how to pick the cheapest one.

51-Foot Ladder

When discussing the proposed border wall between the U.S. and Mexico, then-governor Janet Napolitano remarked, “You show me a 50-foot wall, I’ll show you a 51-foot ladder.” But would this be long enough? In this lesson, we’ll use trigonometric ratios to explore everything about ladders and ladder safety.

Hat tip to Maria Droujkova.

## Nature by Numbers video

Here's a delightful video that shows a nice relationship of numbers, geometry, and nature.

Hat tip to Don Cohen, the Mathman.