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# Curious Facts

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• For any large collection of numbers, the probability that any two have a common factor is 6/pi2
• Pi can be calculated by studying the stars. Using the above fact, Robert Matthews of the University of Aston in Birmingham, UK, calculated the angular distance between the 100 brightest stars in the sky. He then turned these measurements into 1 million pairs of random numbers, and found that around 61 per cent had no common factors. This gave him a value of pi equal to 3.12772, which is approximately 99.6% accurate. 1
• Pi can be calculated using needles and lined paper. If needles are dropped on to the paper, the percentage that fall on the lines should be equal to the needle length divided by the width between the line, all multiplied by 2/pi. This theory was first proposed by the French Mathematician Georges-Louis Leclerc, Comte de Buffon, in 1733. It is known as Buffon’s needle problem.
• The Earth's days are increasing in length by approximately 2 thousandths of a second every century, due to the friction between the water in the oceans, which is pulled by gravity towards the moon, and the surface of the Earth.
• The moon moves 4cm further away from Earth every year. Because the rate of the Earth's spin is slowing down, the speed of the moon's orbit of the Earth increases in order to conserve angular momentum. This increase in speed (relative to Earth) causes it to slowly drift away.
• Warmer water can sometimes freeze faster than colder water. This is know as the Mpemba effect.
• The English astronomer Fred Hayle who coined the term "The Big Bang" in 1949 didn't believe in the Big Bang Theory.

1. Nature 374, 681 - 682 (20 April 1994); doi:10.1038/374681b0: http://www.nature.com/nature/journal/v374/n6524/abs/374681b0.html

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