Perfect Numbers Math
1 the n n n th perfect number has n n n digits.
Perfect numbers math. List of perfect cube numbers 1 to 50. 5 there are infinitely many perfect. It is not known whether there are any odd perfect numbers. The smallest perfect number is 6 which is the sum of 1 2 and 3.
Every perfect number is of the. A perfect number is a positive number that equals the sum of its divisors excluding itself. Perfect number a positive integer that is equal to the sum of its proper divisors. 3 all perfect numbers end in 6 and 8 alternately.
The following is a list of the known perfect numbers and the exponents p that can be used to generate them using the expression 2 p 1 2 p 1 whenever 2 p 1 is a mersenne prime. Are there any odd. Euclid proved that 2 p 1 2 p 1 is an even perfect. In about 300 bc euclid showed that if 2 p 1 is prime then 2 p 1 2 p 1 is perfect.
The discovery of such numbers is lost in prehistory but it is known that the pythagoreans founded c. If x is a perfect cube of y then x y 3 therefore if we take out the cube root of a perfect cube we get a natural number and not a fraction. For example 8 is a perfect cube because 3 8 2. A perfect cube is a number which is equal to the number multiplied by itself three times.
All even perfect numbers are of this form. 2 all perfect numbers are even. If the sum of the factors is equal to 18 then 18 is a perfect number. Are there infinitely many perfect numbers.
525 bce studied perfect numbers for their mystical properties. Hence 3 x y. A number is perfect if the sum of its proper factors is equal to the number. This is also known as its aliquot sum.
A perfect number n is a positive integer which is equal to the sum of its factors excluding n itself. 4 euclid s algorithm to generate perfect numbers will give all perfect numbers i e. The first four perfect. To find the proper factors of a number write down all numbers that divide the number with the exception of the number itself.
At this time it is unknown how many perfect numbers truly exist. In 1887 sylvester conjectured and in 1925 gradshtein proved that any odd perfect number must have at least six distinct prime factors ball and coxeter 1987.