# Cool Facts

## Sphericons

This is neat…. a sphericon is a 3-dimensional geometric solid with a single continuous face and two edges (sort of like a MÃ¶bius strip). The sphericon rolls along a wobbley path but ends up traveling in a straight line! Over at Fold Play, someone turned a pie into a sphericon – watch as it rolls …

## Mathematicians offer elegant solution to evolutionary conundrum

From the ScienceDaily: “UBC researchers have proffered a new mathematical model that seeks to unravel a key evolutionary riddle–namely what factors underlie the generation of biological diversity both within and between species.” Their research can be found in Science:Michael Doebeli, Iaroslav Ispolatov. Complexity and Diversity. Science, 2010: 328 (5977): 494-497 DOI: 10.1126/science.1187468 Keep up the …

## Freshman’s dream and sophomore’s dream

For those who haven’t heard of this yet, the freshman’s dream is given to the (common) error: (x + y)n = xn + yn, where n is usually a positive integer greater than 1 (can be real too). You’d be surprised how many university students make this mistake! Simplying looking at n=2 shows why it doesn’t work in general: (x + y)2 = …

## Shoe Lacing Math

How many ways are there to tie your shoes? Depends on the shoes, but Ian has done some calculations (under certain assumptions) to show there are over 2 trillion ways! Mathematician, Burkard Polster, published an article in the journal Nature (December 2002) about the mathematics of shoe lacing. His calculation for the number of ‘real-world’ …

## Bike with square wheels

I’m back to my regular update schedule. I was just visiting Macalester College and saw that they had the tricycle pictured below! I have seen pics on the internet of it but didn’t know where it existed. The original was created in 1997 (and replaced in 2004) by Professor Wagon (not Professor Bike) and rolls …

## Making change

Consider the following hypothetical situation: You are a cashier and you have to give the customer \$0.40 in change, however, you have no nickels left in your till. The goal is to minimize the number of coins that the customer receives. How do you do it? Well this actually happened, and the process the cashier …

## The average person has one testicle and one ovary…

The first one is how to cheer up your friend… Just don’t tell him he should have one ovary 😛 This actually appeared in a textbook…

## Deck Shuffling

Cool fact: If you thoroughly shuffle an ordinary deck of 52 playing cards, chances are that the resulting arrangement of cards has never existed before (via Reddit and Reddit). Quoting from the math subreddit: “Proof — easy numeric comparison. There are 52! possible orderings of a deck, and I’m assuming all are equally likely after …

## Memorizing Pi – World Records and Techniques

How many digits of pi do you have memorized? But seriously… is it 3? 5? 10? more than 30? If it’s more than 30 pat yourself on the back because that’s a great accomplishment! If it’s only a few, then no worries. Below we will teach you some techniques that can be used to conquer …

## Topological Poker

This is interesting. RandomPairing over at the math subreddit listed some rules for a game called Topological Poker (aka Dicks and Hoes), which I assume he created himself. [I did a google search for “Topological Poker” and only got the subreddit, and then did a search for “Dicks and Hoes” and got a bunch of …