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Can you solve this 'simple' puzzle that has bamboozled ace math students around the world?

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Take a good look at the image above as we are about to drop what is supposedly a 'simple' puzzle on you to work out. The question appeared on maths tests way back in 1995 and advanced maths students across 16 countries had some serious issues trying to solve it.

The question is as follows: A string is wound symmetrically around a circular rod. The string goes exactly 4 times around the rod. The circumference of the rod is 4cm and the its length is 12cm. Find the length of the string and show all of your work. Can you work it out?

The reason it is considered to be an easy question is because it does not require any advanced mathematical skills to solve. The puzzle was created by the International Association for the Evaluation of Educational Achievement (IEA) to test maths literacy in 16 countries that year. The best performing country was Sweden where a paltry 24% of students tested managed to correctly solve the problem.

That is an incredible score though when compared to the worst performing country, the United States, where only 4% of the students tested managed to adequately solve the puzzle. Overall, the IEA reported that 10% of all students tested around the world managed to get the correct answer while a further 2% were on the right track getting the puzzle partially right. Not what the IEA were expecting from a question considered to be easier than many others on the test.

For those of you who are shouting "Give me a hint" then the best strategy for solving the puzzle is to think slightly outside the spatial box and imagine the cylinder and string flattened out into a rectangle. If you are still struggling for a direction to go then we will give you an even bigger hint - just think Q.E.D...

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