The 22 million digit number … and the amazing maths behind primes

It is a quite extraordinary figure. Dr Curtis Cooper from the University of Central Missouri has found the largest-known prime number – written (274207281)-1. It is around 22m digits long and, if printed in full, would take you days to read. Its discovery comes thanks to a collaborative project of volunteers who use freely available software called GIMPS (Great Internet Mersenne Prime Search) to search for primes.

A number which can only be divided by itself and 1 without a remainder is called a prime number. Here is a list of the primes less than 100: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97. Read more…

How to vet nonprofits before you give

Charity solicitations are as much a part of the holiday season as decorations. If you give, it’s a good idea to know what the nonprofit organization does with your money. Here’s one way: use ProPublica’s Nonprofit Explorer, a tool for researching the financial details of nonprofits.

Organizations that receive a tax exemption from the Internal Revenue Service and take in at least $50,000 a year have to file an annual report, called a Form 990, which can serve as a guide to how they operate and what their programs are. Read more…

11 body fluids we couldn’t live without

How is a human being like a fish?

Just as a fish never stops to think about the water in which it spends its entire life, so do many human beings rarely pause to consider the body fluids that make our lives possible.

Though not always fit for polite conversation, even the less pleasant among them play a crucial role in maintaining health. By learning a bit more about 11 of these body fluids, we can develop a deeper appreciation for the beauty and complexity of our own biology. What exactly are these fluids, and what often unheralded contributions do they make? Read more…

A dozen interesting facts about roses

There are over 100 species and thousands of cultivars of roses. They vary in color, shape and size and all but one rose species have 5 petals.

Here are a dozen interesting facts about roses.

1. Black roses are an illusion of the mind

There are no roses that are black in color, although there are a few species of roses that come close. The Turkish Halfeti rose, also known as “The Black Rose of Turkey”, is an extremely rare breed that appears pitch-black to the eye, but in fact is a dark reddish-crimson color. Read more…

Is it really OK to eat food that’s fallen on the floor?

By Paul Dawson, Clemson University

When you drop a piece of food on the floor, is it really OK to eat if you pick up within five seconds? This urban food myth contends that if food spends just a few seconds on the floor, dirt and germs won’t have much of a chance to contaminate it. Research in my lab has focused on how food and food contact surfaces become contaminated, and we’ve done some work on this particular piece of wisdom.

While the “five-second rule” might not seem like the most pressing issue for food scientists to get to the bottom of, it’s still worth investigating food myths like this one because they shape our beliefs about when food is safe to eat. Read more…

Steam power and Jell-O

Heron of Greece invented steam power in 50 BC. But the leaders of the day thought that it would cause unemployment and the invention ran out of steam.

The steam engine reappeared in the 1600s in Ferdinand Verbiest’s steam car and then years later again, in 1804, when English inventor Richard Trevithick introduced the steam locomotive in Wales.

In 1815, George Stephenson built the world’s first workable steam locomotive. Read more…

How we showed ‘sleeping on it’ really is the best way to solve a problem

By Padraic Monaghan, Lancaster University

Have you ever struggled to finish a level of Candy Crush or complete a Sudoku puzzle in the evening but breezed through it the following morning? The reason may please anyone who’s been told they spend too much time in bed asleep.

We tend to think of sleep as a period of recuperation, giving us enough down-time to enable our muscles and thought processes to operate effectively. However, sleep can also have an active function. As far back as Aristotle, the fact that we dream has suggested to people that sleep could enhance the mind’s self-communication. And, more recently, there’s been a surge of research into the consequences of sleep as an active process, rather than just a rest. Read more…

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