Topics in Number Theory |
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Pascal's Triangle |

Perfect Numbers |

Fermat's Last Theorem |

Magic Squares |

Moessner's Magic |

Pascal's triangle was first introduced by the Chinese mathematician Yang Hui, but it got it's name from Blaise Pascal who 500 years later rediscovered it along with Omar Khayyam. The triangle is used to look for the probability of any particular event to occur. There are many other things that can be found in the triangle. Listed below are a few of them and how to achieve them.
This can go on as long as anyone wants it to go.
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Contributed by Cris Edelman | ||||||||||||||||

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The Pythagoreans produced a theory of numbers comprised of numerology and scientific speculation. In their numerology, even numbers were feminine and odd numbers masculine. The numbers also represented abstract concepts such as 1 stood for reason, 2 stood for opinion, 3 stood for harmony, 4 stood for justice, and so on. Their arithmetica had a theory of special classes of numbers. There were “perfect” numbers of two kinds. The first kind included only 10, which was basic to the decimal system and the sum of the first four numbers 1 + 2 + 3 + 4 = 10. The second kind of “perfect” numbers were those equal to the sum of their proper divisors. A perfect number is a positive integer that is equal to the sum of it divisors. However, for the case of a perfect number, the number itself is not included in the sum. The Greeks called a number such as 6 or 28 a “perfect” number because the sum of the proper divisors in each case is equal to the number; the proper divisors of 6 are 1, 2, and 3, and their sum is 6.
Although perfect numbers are regarded as arithmetical curiosities, their study has helped to develop the theory of numbers. Euclid proved that a number n of the form (2 The Neoplatonists Nicomachus of Gerasa and Iamblichus of Chalcis listed these perfect numbers and concluded that they follow a pattern: They alternately end in a 6 or an 8, and there is one perfect number for each interval from 1 to 10, 10 to 100, 100 to 1,000 and 1,000 to 10,000. They conjectured that both parts of the pattern would continue, but in this they were wrong. The fifth perfect number, which was discovered in the fifth century, corresponds to n = 13 and is 33,550,336, with eight digits rather than six. In addition, the sixth perfect number, like the fifth, ends with a six.
In 1961, the twentieth perfect number was found. It contains 2,663 digits in the decimal representation and corresponds to the case where n = 4,423. Today, twenty-three perfect numbers are known. The largest of these is 2
In 1757, Leonhard Euler probed that every even perfect number must be of Euclid’s form. It has also been proven that every even perfect number must end in six or eight and if it ends in six, the digit preceding it must be odd. No one has as yet discovered an odd perfect number, but it is known that none exist below 10
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Contributed by Kristen Shelton | ||||||||||||||||

References Calinger, Ronald, Classics of Mathematics, Prentice Hall, New Jersey 1995. Boyer, Carl B., A History of Mathematics, John Wiley & Sons, Inc., New York 1989.
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Fermat's (pronounced Fer mah') Last Theorem is the name given to a puzzling problem that Pierre Fermat (1601-1665), a French amateur mathematician, created. Although he made contributions to several branches of math, his preferred area was in number theory - the relationships that exist among numbers.
It was while he was studying a copy of an ancient work on number puzzles that he
started pondering about Pythagoras' (pronounced Pi tha' gor us) equation about
right triangles. Pythagoras, a Greek mathematician who lived more than 2000
years before Fermat, proved that squaring the lengths of the two legs of a right
triangle and adding them together would be equal to the square of the length of the
longest side, usually stated as a
As Fermat meditated on this equation, he began speculating on a related one,
a ^{n} + b^{n} = c^{n}, when 'n'
is an integer greater than 2.The genius then mischievously added, "I can prove this but don't have enough room to write it in the margin." For 300 years mathematicians have tried to find the proof or explanation that Fermat didn't write, Fermat's Last Theorem. The American mathematician, Andrew Wiles, created a proof, though it took him eight years. The proof was published in Annals of Mathematics in 1995, 330 years after Fermat's death, but obviously it was not Fermat's proof, since Wiles used math not available in the 17th century. Will someone discover Fermat's proof? That question remains unanswered.
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Contributed by Charlene Evans
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References: Singh, Simon. Fermat's Enigma: The Epic Quest to Solve the World's Greatest Mathematical Problem. New York: Doubleday, 1997. Ball, W.W. Rouse. A Short Account of the History of Mathematics. 1908. Web address for more information. | ||||||||||||||||

What’s so magic about magic squares, anyway??
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Originally, magic squares were of little mathematical significance when they were discovered around 2000 BC by Yu the Great, a Chinese emperor. During the reign of Yu the Great, he encountered two animals that were said to have magical powers, a tortoise and a dragon horse. On the back of the tortoise was a pattern or symbol, now known as the lo shu, which represented a square array of numbers. These numbers were first depicted by knots tied in strings, with white knots for odd numbers and black knots for even. These mystical squares found their way to Japan, India, and the Middle East. There is evidence of magic squares being found in Arabia and even in Hebrew writings. So, why all the magic connected with these squares? The ancient people thought the squares were magic, or at least possessed some sort of good luck, because the sums of the numbers in each row, in each column and in each major diagonal was the same. Silver plates used to be engraved with magic squares and prescribed as a charm against the plague and other serious illnesses. They were also connected to alchemy and astrology and were used by fortune tellers to decorate bowls and amulets. During the thirteenth century, a mathematician name Yang Hui, actually began to study magic squares, referred to as vertical and horizontal diagrams. He extrapolated the ideas to construct a magic circle where the sum of the numbers on any diameter or along any of the concentric circles would be the same sum. Yang Hui also generalized some rules for constructing magic squares. In a 4X4 square there are 16 squares. Using the numbers 1 through 16, fill in the matrix starting with upper left corner and counting down. Number five will be next to number 1. If the numbers at the corners of the inner square and the outer square are transposed, or swapped, a magic square will result with all rows, columns and diagonals adding up to 34. Albrecht Durer is credited with showing the first magic square in print. This magic square appeared in an engraving and was a 4X4 square with all rows, columns and diagonals summing to 34. In the bottom row the numbers appear in the following order: 4, 15, 14, 1. The year that the engraving was made was worked into these numbers. Can you guess the year of the engraving? The engraving’s date was 1514.
Magic Squares were studied in France and in Poland in the seventeenth century and methods of constructing magic squares were revealed. Three dimensional magic squares were also constructed by Adamas Kochansky in 1686. During the nineteenth century, magic squares were taken seriously and were applied to problems dealing with probability and analysis. A type of magic square, developed by Euler, referred to as the Greco-Latin square, had use in designing experiments. As recently as 1978, Allen Adler, a mathematician, has published papers about magic squares. His opinion is that most mathematicians view magic squares as a waste of valuable time because entertainment or recreation is the most that one could get from reaching a solution. However, he is convinced that the use of magic squares in the classroom could teach factorization into primes and association. Allen Adler has a strong message that reaches way beyond the topic of mathematics and the notion of magical experiences. On his web page that is dedicated to magic squares, there is an autobiography that reveals the course of study and exploration that has progressed. Of his experience he writes: “I can trace the precise evolution of these ideas and results, but what is more important for students and others, . . . unlike the ancient methods and results for magic squares, which one finds repeated over and over again down the centuries, what one finds here is alive and growing. It also serves to show that anyone can follow the path to original discoveries by following his or her curiosity wherever it leads, and this is a lesson that needs very much to be communicated.”Perhaps there certainly was magic in these squares for Mr. Adler. But you won’t find any amulet around his neck. Link to his web page to learn more:http://mathforum.com/alejandre/magic.square/adler/
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Contributed by Cynthia Schmidt
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References:
- The National Council of Teachers of Mathematics. (1969).
- Historical Topics for the Mathematics Classroom. Washington, DC: Heck, W. and Fey, J.
- http://mathforum.com/alejandre/magic.square/adler/
- http://forum.swarthmore.edu/alejandre/magic.square/
- http://www.roma.unisa.edu.au/07305/
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Number sequences can be very interesting and thought provoking. Most number sequences involve building some kind of pattern and seeing what comes next. One well-known number sequence is Pascal's triangle. A number sequence not so well-known is Moessner's magic. Let's consider the sequence of counting numbers: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, . . . . Now, cross out every second number, leaving 1, 3, 5, 7, 9, 11, 13, 15, . . . ; form the cumulative totals of these numbers: 1, (1 + 3), (4 + 5), (9 + 7), (16 + 9), (25 + 11), (36 + 13), (49 + 15) . . . ; and you get the sequence of consecutive squares: 1, 4, 9, 16, 25, 36, 49, 64, . . . ! This transformation of the sequence of counting numbers into another was first discovered and explored by Alfred Moessner in the early 1950s. Now, suppose we start with the sequence of counting numbers just like before, but now we take out every third number and add what's left. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, . . . 1, 2, 4, 5, 7, 8, 10, 11, 13, 14, . . . 1, (1 + 2), (3 + 4), (7 + 5), (12 + 7), (19 + 8), (27 + 10), (37 + 11), (48 + 13) + (61 + 14) ... 1, 3, 7, 12, 19, 27, 37, 48, 61, 75, . . . Now, remove every second number in the new list and add the remaining numbers. 1, 7, 19, 37, 61, . . . 1, (1 + 7), (8 + 19), (27 + 37), (64 + 61), ... 1, 8, 27, 64, 125, . . .
Amazing! This is the sequence of cubes.
Now, if you go through the same procedure again, this time crossing out every fourth number at the beginning, the result should not be surprising. You end up with the sequence of fourth powers: 1, 16, 81, 256, . . . . In general, taking out the Try it with higher powers. It will work.
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Contributed by Amy Troutman
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References:
- Conway, John H.and Richard K. Guy. The Book of Numbers. New York: Copernicus, 1995.
- URL http://www.sciencenews.org/sn_arch/11_16_96/mathland.htm 6/10/00 5:00pm
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