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Special Numbers PHI Perfect Numbers Harmonic Numbers.

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Presentation on theme: "Special Numbers PHI Perfect Numbers Harmonic Numbers."— Presentation transcript:

1 Special Numbers PHI Perfect Numbers Harmonic Numbers

2 Phi – The Phinest number around This is the Golden Ratio. It can be derived from: Since n 2 -n 1 -n 0 =0 n 2 -n-1=0 n 2 =n+1 The root of which is 0.5(5 1/2 +1) Which can be approximated to:

3 Phi to the first 1000 decimal places Phee Phi Pho Phum I smell the blood of a Mathematician


5 Check this out! You can make a ruler based on this ratio looking like this: And you can see that this ratio appears everywhere!


7 In nature

8 So what does it all mean? Some people take this to be a proof that god exists as all of these things could not be based on this same ratio purely by chance. This suggests a creator or designer… ?

9 Perfect Numbers A perfect number is a positive integer which is the sum of all its positive divisors (e.g. 6 being the sum of 1, 2 and 3) The first 4 perfect numbers are 6, 28, 496 and = = = =8128 (The first records of these came from Euclid around 300BC)

10 This starts going up very quickly As you can see: 6, 28, 496, 8128, , , , , , , You can take my word for it or if you want you can work them out. =P

11 How to find a perfect number: According to Euclid, if you start with 1 and keep adding the double of the number preceding it until the sum is a prime number e.g =7 Then take the last number (4) and the sum (7) then you should get a perfect number 4x7=28 Also from …+2 k-1 =2 k -1 We can rearrange to 2 k-1 (2 k -1) should be a perfect number (so long as 2 k -1 is prime).

12 Nicomachus (c. 60 –c. 120) Nicomachus added some extra rules for perfect numbers: 1.)The nth perfect number has n digits. 2.) All perfect numbers are even. 3.) All perfect numbers end in 6 and 8 alternately. 4.) Euclid's algorithm to generate perfect numbers will give all perfect numbers i.e. every perfect number is of the form 2 k-1 (2k - 1), for some k > 1, where 2 k - 1 is prime. 5.) There are an infinite amount of perfect numbers. At this time however, only the first 4 perfect numbers had been found, do these rules apply to the rest of them? Check

13 The 4 th rule Take the example of when k=11: 2 10 ( )=1024x2047= Therefore the 4 th rule is also incorrect Check again

14 5 th rule Cant dispute it. To date there are 39 known perfect numbers The last of which is: ( ).

15 Perfect Harmony Perfect numbers are all thought to be Harmonic numbers integer whose divisors have a harmonic mean that is an integer. e.g. 6 which has the divisors 1, 2, 3 and 6 And 140: =5

16 This sequence goes a little bit like this: 1, 6, 28, 140, 270, 496, 672, 1638, 2970, 6200, 8128, 8190 … Including the perfect numbers: 6, 28, 496, 8128 However: This could also be as wrong as Nicomachus so beware!

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