- Irrationality Of E 17/10/2010 01:00
Prove that e is irrational.
Problem ID: 377 (17 Oct 2010) / Difficulty: 4 star - Rectangle Construction 17/10/2010 01:00
Find the connection between the constructed length and the original rectangle.
Problem ID: 376 (17 Oct 2010) / Difficulty: 2 star - Inscribed Circle In Isosceles Triangle 16/08/2010 01:00
Find the radius of the circle inscribed inside the isosceles triangle.
Problem ID: 375 (16 Aug 2010) / Difficulty: 2 star - Multiplying Magic Square 16/08/2010 01:00
Show how the values 1, 2, 4, 8, 16, 32, 64, 128, and 256 can be placed in a 3x3 square grid so that the product of each row, column, and diagonal gives the same value.
Problem ID: 374 (16 Aug 2010) / Difficulty: 3 star - Polynomial Roots 07/08/2010 01:00
Prove that the roots of the polynomial, xn + cn-1xn-1 + ... + c2x2 + c1x + c0 = 0, are irrational or integer.
Problem ID: 373 (07 Aug 2010) / Difficulty: 3 star - Hops And Slides But Never Square 07/08/2010 01:00
Prove that the minimum number of moves to completely reverse the positions of the coloured counters can never be square.
Problem ID: 372 (07 Aug 2010) / Difficulty: 3 star - Irrationality Of Pi 24/12/2009
Prove that π is irrational.
Problem ID: 371 (24 Dec 2009) / Difficulty: 4 star - Square And Round Plugs 24/12/2009
Which fits better... a round plug in a square hole or a square plug in a round hole?
Problem ID: 370 (24 Dec 2009) / Difficulty: 2 star - Algebraic Cosine 30/11/2009
Prove that cos(x) is algebraic if x is a rational multiple of Pi.
Problem ID: 369 (30 Nov 2009) / Difficulty: 4 star - Inscribed Square 30/11/2009
Find the side length of the square inscribed inside the right angled triangle.
Problem ID: 368 (30 Nov 2009) / Difficulty: 2 star - Infinite Circles 15/11/2009
What fraction of the large red circle do the infinite set of smaller circles represent?
Problem ID: 367 (15 Nov 2009) / Difficulty: 4 star
- Stage 1::[problem*] How do you see it ? Here are some short problems for you to try. Talk to your friends about how you work them out.
- Stage 1::[Featured Solution] Odd times Even Not that many solutions but some good justifications offered here.
- Stage 1::[Article] From objects and images to mathematical ideas This article looks at how images, concrete apparatus and representations can help students develop deeper understandings of abstract mathematical ideas.
- Stage 1::[problem] Models in mind This article looks at how models support mathematical thinking about numbers and the number system
- Stage 2::[problem*] Let's divide Up! Look at different ways of dividing things. What do they mean? How might you show them in a picture, with things, with numbers and symbols?
- Stage 2::[problem*] How do you see it ? Here are some short problems for you to try. Talk to your friends about how you work them out.
- Stage 2::[Featured Solution] Square subtraction This challenge produced some thoughtful ideas and reasons that would lead to a proof - very good for primary school children!
- Stage 2::[Article] From objects and images to mathematical ideas This article looks at how images, concrete apparatus and representations can help students develop deeper understandings of abstract mathematical ideas.
- Stage 2::[problem] Models in mind This article looks at how models support mathematical thinking about numbers and the number system
- Stage 3::[problem*] What numbers can we make? Imagine we have four bags containing a large number of 1s, 4s, 7s and 10s. What numbers can we make?
- Stage 3::[problem**] Always a multiple? Think of a two digit number, reverse the digits, and add the numbers together. Something special happens...
- Stage 3::[problem**] Take Three From Five Caroline and James pick sets of five numbers. Charlie chooses three of them that add together to make a multiple of three. Can they stop him?
- Stage 3::[problem**] What numbers can we make now? Imagine we have four bags containing numbers from a sequence. What numbers can we make now?
- Stage 3::[Featured Solution] Magic Letters We received lots of insightful comments to this problem.
- Stage 3::[Article] From objects and images to mathematical ideas This article looks at how images, concrete apparatus and representations can help students develop deeper understandings of abstract mathematical ideas.
- Stage 3::[Game] Cubic Net This is an interactive net of a Rubik's cube. Twists of the 3D cube become mixes of the squares on the 2D net. Have a play and see how many scrambles you can undo!
- Stage 3::[Game] Diamond Collector Collect as many diamonds as you can by drawing three straight lines.
- Stage 3::[problem] Models in mind This article looks at how models support mathematical thinking about numbers and the number system
- Stage 4::[problem*] Factorising with Multilink Can you find out what is special about the dimensions of rectangles you can make with squares, sticks and units?
- Stage 4::[problem*] Pair Products Choose four consecutive whole numbers. Multiply the first and last numbers together. Multiply the middle pair together. What do you notice?
- Stage 4::[problem**] Take Three From Five Caroline and James pick sets of five numbers. Charlie chooses three of them that add together to make a multiple of three. Can they stop him?
- Stage 4::[problem**] What numbers can we make now? Imagine we have four bags containing numbers from a sequence. What numbers can we make now?
- Stage 4::[Article] From objects and images to mathematical ideas This article looks at how images, concrete apparatus and representations can help students develop deeper understandings of abstract mathematical ideas.
- Stage 4::[Game] Cubic Net This is an interactive net of a Rubik's cube. Twists of the 3D cube become mixes of the squares on the 2D net. Have a play and see how many scrambles you can undo!
- Stage 5::[problem**] Maths Shop Window Make a functional window display which will both satisfy the manager and make sense to the shoppers
- Stage 5::[Featured Solution] Particularly general There were three nice solutions to this advanced problem concerning generic examples. Perhaps younger students might like to try to work through one of them, whereas older students might like to compare them.
- Stage 5::[Article] From objects and images to mathematical ideas This article looks at how images, concrete apparatus and representations can help students develop deeper understandings of abstract mathematical ideas.
- Stage 5::[Game] Cubic Net This is an interactive net of a Rubik's cube. Twists of the 3D cube become mixes of the squares on the 2D net. Have a play and see how many scrambles you can undo!
- Readers respond to "A Man-made Contagion" and Other Articles
FLU SECURITY [More]
- Traveling Salesman: A Seemingly Unsolvable Problem Offers a Glimpse of the Limits of Computation
Is it hopeless to try to compute the shortest route to visit a large number of cities? Not just a good route but the guaranteed shortest. The task is the long-standing challenge known as the traveling salesman problem, or TSP for short.
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- Down with Double Data Fees!
We the People of the United States, in Order to form a more perfect Lifestyle, establish Fairness, ensure blood pressure Tranquility, provide for the common Text Messager, promote less Outrage and secure Cell phone Service that’s anywhere near as good as it is in Other Countries, do ordain and establish this Cellular Bill of Rights.
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- In Their Prime: Mathematicians Come Closer to Solving Goldbach's Weak Conjecture
One of the oldest unsolved problems in mathematics is also among the easiest to grasp. The weak Goldbach conjecture says that you can break up any odd number into the sum of, at most, three prime numbers (numbers that cannot be evenly divided by any other number except themselves or 1). For example: [More]
- Ancient Time: Earliest Mayan Astronomical Calendar Unearthed in Guatemala Ruins
An excavation of an archaeological site in Guatemala has uncovered Mayan astronomical records dating to the ninth century A.D. The tabulated numbers, which predate existing Mayan astronomical documents by several hundred years, chart the motion of the moon and also seem to relate to the orbits of Mars and Venus. (And good news: they do not predict the world will end this year --in fact, some of the numbers appear to refer to dates far in the future.)
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- Does Digital Piracy Really Hurt Movies?
The shadowy nature of illegal media downloading makes it difficult for researchers to analyze the true relation between piracy and lost sales. Does every movie download represent a theater ticket left unpurchased, as the movie industry contends? Or are most downloaders people who never would have bought a ticket in the first place?
[More]
- Spy-High: Amateur Astronomers Scour the Sky for Government Secrets
Earlier this year Iran's defense minister put the world on notice: His nation had developed the ability to "easily" watch spacewalking astronauts from the ground. The announcement was largely ignored, in part because it made the minister sound like a James Bond villain. The boast was also a bit anticlimactic, given that even amateur astronomers are already recording in detail what happens in low Earth orbit. Both the technology involved and the techniques used to observe satellites and even the occasional astronaut perched outside the International Space Station (ISS) are improving, much to the presumed chagrin of governments looking to keep certain on orbital activity confidential. [More]
- Math Rules
In his new book, In Pursuit of the Unknown: 17 Equations That Changed the World , Ian Stewart recounts one of the worst jokes in the history of science. You can develop your own setup from first principles once you know the punch line: “The squaw on the hippopotamus is equal to the sum of the squaws on the other two hides.” Never mind how Native Americans were in possession of a hippopotamus--the important thing is that the Pythagorean theorem is so well known that comedy writers consider it fair game even if that game couldn’t possibly be found on the correct continent.
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- For a Healthier Country,
Overhaul Farm Subsidies
Some years ago two nutrition experts went grocery shopping. For a dollar, Adam Drewnowski and S. E. Specter could purchase 1,200 calories of potato chips or cookies or just 250 calories worth of carrots. It was merely one example of how an unhealthy diet is cheaper than a healthy one. This price difference did not spring into existence by force of any natural laws but largely because of antiquated agricultural policies. Public money is working at cross-purposes: backing an overabundance of unhealthful calories that are flooding our supermarkets and restaurants, while also battling obesity and the myriad illnesses that go with it. It is time to align our farm policies with our health policies.
[More]
- A New Report Sheds Light on Problems Plaguing Russia's Space Program
Last November, Russia launched a widely anticipated mission to the Martian moon Phobos. The craft would gather samples from the moon’s surface to help determine if future space crews could obtain valuable supplies of oxygen there en route to Mars. For Russia, the mission was supposed to mark a “cavalry charge” that would redeem a quarter-century of interplanetary impotence. Instead it turned into a cosmic humiliation when the craft died shortly after takeoff and fell back to Earth.
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- Probability and the Birthday Paradox
Key concepts [More]
- What the fractal?
As part of my job at RiAus I get asked to write the occasional blog about an upcoming event. I wrote this for an event that occured last week about fractal geometry with the amazing Prof. Michael Barnsley . It was a great event and my blog post was just a little teaser for it.
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- Rhythm and Music Help Math Students
Stuck on a tricky math problem? Start clapping. Grade school kids who learned about fractions through a rhythm-and-music-based curriculum outperformed their peers in traditional math classes. The work is in Educational Studies in Mathematics . [Susan Joan Courey et al., " Academic music: music instruction to engage third-grade students in learning basic fraction concepts "]
[More]
- High Status Breeds Feelings of Trust
High status confers a rosy worldview, according to research available online last August in Organizational Behavior and Human Decision Processes . Psychologists asked college students to write essays about having more prestige than others or being low on the totem pole, thus priming them to think of themselves as having either high or low status. Then the students were told they could send $10 to an unseen partner; the money would be tripled, and the phantom partner would return as much as he wanted. Forty percent of the high-status group sent the $10 versus 12 percent of the low-status group.
[More]
- Snowflake Growth Successfully Modeled from Physical Laws
Windswept from cloud to cloud until they flutter to Earth, snowflakes assume a seemingly endless variety of shapes. Some have the perfect symmetry of a six-pointed star, some are hexagons adorned with hollow columns, whereas others resemble needles, prisms or the branches of a Christmas tree.
[More]
- Juice Box Geometry
Key concepts [More]
- Readers Respond to "Can We Feed the World and Sustain the Planet?" and Other Articles
ENTOMOLOGICAL ETHICS [More]
- How to Make Science and Tech Jobs More Enticing to Undergrads
The number of U.S. undergraduate degrees being awarded in most STEM disciplines (science, technology, engineering and math) has risen steadily in recent years{link to G Sci page}. Yet some American employers say they are having trouble finding candidates to fill STEM jobs. The mismatch is not occurring because of an actual shortage of graduates; the numbers of job openings and new degree holders align fairly closely. And the shortfall is not because more foreign-born students are returning home after earning U.S. degrees, as has been rumored lately.
[More]
- The Not-So-Hot Hand
Reggie Miller, Michael Jordan, Kobe Bryant. They’ve all gone on seemingly memorable shooting streaks. But past research has shown that the so-called hot hand is a myth, rooted in our tendency to see patterns where there are none.
[More]
- A Brief History of Clocks
Humankind’s efforts to tell time have helped drive the evolution of our technology and science throughout history. The need to gauge the divisions of the day and night led the ancient Egyptians, Greeks and Romans to create sundials, water clocks and other early chronometric tools. Western Europeans adopted these technologies, but by the 13th century, demand for a dependable timekeeping instrument led medieval artisans to invent the mechanical clock. Although this new device satisfied the requirements of monastic and urban communities, it was too inaccurate and unreliable for scientific application until the pendulum was employed to govern its operation. The precision timekeepers that were subsequently developed resolved the critical problem of finding a ship’s position at sea and went on to play key roles in the industrial revolution and the advance of Western civilization.
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