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Originally Posted by El Loro:

496 and 8128

 

They're perfect numbers.

The numbers which divide into 6 (apart from 6) are 1,2 and 3. 1+2+3=6

28  = 1,2,4,7,14. 1+2+4+7+14=28

496 = 1,2,4,8,16,31,62,124,248  1+2+4+8+16+31+62+124+248=496

8128 = 1,2,4,8,16,32,64,127,254,508,1016,2032,4064  1+2+4+8+16+32+64+127+254+508+1016+2032+4064=8128

Well done El Loro  brilliant 

Moonie

All perfect numbers found so far have been even numbers, but it's never been proved that there aren't any odd numbered perfect numbers.

 

Ignore 1

The only proper divisor of 3 is 1. Same for 5 and 7.

The proper divisors of 9 are 1 and 3 but that totals 4.

!! and 13 - only 1 is a proper number

15 - proper divisors are 1,3,and 5 totals 9

17 and 19 - only 1 is a proper number

21 - proper divisors are 1,3, and 7 totals 11

23 - only proper divisor is 1

25 - 1 and 5 totals 6

27  - 1, 3 and 9 totals 13

And so on. If you find an odd number whose proper divisors total itself then you will be the first person in the world to do so. Or prove that there are no odd perfect numbers.

El Loro
Originally Posted by machel:
Originally Posted by moonie:
Originally Posted by Pengy:

as soon as I saw numbers I ran - maths is not my strong point 

I have to admit Pengy its not one of my strong points either. I was just watching a  television program where that sequence came up. So I cant claim any credit for it whatsoever 

was that Lewis?

Yep, it was Machel 

Moonie
Originally Posted by El Loro:

496 and 8128

 

They're perfect numbers.

The numbers which divide into 6 (apart from 6) are 1,2 and 3. 1+2+3=6

28  = 1,2,4,7,14. 1+2+4+7+14=28

496 = 1,2,4,8,16,31,62,124,248  1+2+4+8+16+31+62+124+248=496

8128 = 1,2,4,8,16,32,64,127,254,508,1016,2032,4064  1+2+4+8+16+32+64+127+254+508+1016+2032+4064=8128

 

Damn you got there before me El Loro

Temps
Originally Posted by Saint:

Hmmm Primary Mathematics Today states the vast majority of mathematical knowledge is possessed to massage the ego and is of no real use in an every day setting.

It also says the answer is -22

Yes, but -22 is the answer to a sum. The question that was posed here was not a sum.

 

If you check 'Primary Mathematics Today' has an asterisk against '-22'

 and the asterisk says 'This is only the answer if the original question was a sum.'

Extremely Fluffy Fluffy Thing
Originally Posted by KaffyBaffy:

I still don't know what a perfect number is.  Is it a number that always did what it was told, kept its room tidy, ate its greens and always did its homework?

In number theory, a perfect number is a positive integer that is equal to the sum of its proper positive divisors, that is, the sum of its positive divisors excluding the number itself (also known as its aliquot sum). Equivalently, a perfect number is a number that is half the sum of all of its positive divisors (including itself) i.e.σ1(n) = 2n.


Well you did ask Kaffy 

Moonie

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