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-   -   Maths: why does 987654321 / 123456789 = 8.000000073 (http://archives1.twoplustwo.com/showthread.php?t=549199)

john kane 11-18-2007 07:45 PM

Maths: why does 987654321 / 123456789 = 8.000000073
 
i have spent many time at work typing into my calculator stuff like this. anyone know why if you do 987654321 divided by 123456789 it comes to such an eerie number, so close to 8, but not quite?

Styhn 11-18-2007 07:58 PM

Re: Maths: why does 987654321 / 123456789 = 8.000000073
 
Uhm.. Because 123456789 * 8 is almost equal to 987654321? Not trying to sound smug but that's all there is to it I think [img]/images/graemlins/smile.gif[/img]

felson 11-18-2007 08:01 PM

Re: Maths: why does 987654321 / 123456789 = 8.000000073
 
because

felson 11-18-2007 08:10 PM

Re: Maths: why does 987654321 / 123456789 = 8.000000073
 
eh, i'll explain a little. if you compare successive lines in the picture, you can see what is happening. it's a consequence of the fact that eight is two less than ten, the base of the decimal system. you would get a similar pattern with 6 in octal, or 14 in hexadecimal.

thylacine 11-18-2007 09:39 PM

Re: Maths: why does 987654321 / 123456789 = 8.000000073
 
[ QUOTE ]
i have spent many time at work typing into my calculator stuff like this. anyone know why if you do 987654321 divided by 123456789 it comes to such an eerie number, so close to 8, but not quite?

[/ QUOTE ]

Consider 10/81 and 80/81 in decimal.

Also consider 1/9 in decimal, then square it.

eviljeff 11-18-2007 10:54 PM

Re: Maths: why does 987654321 / 123456789 = 8.000000073
 
I love this thread

mbillie1 11-18-2007 11:57 PM

Re: Maths: why does 987654321 / 123456789 = 8.000000073
 
because numbers are rigged, for more evidence see: fulltiltpoker.com

vetiver 11-19-2007 12:35 AM

Re: Maths: why does 987654321 / 123456789 = 8.000000073
 
[ QUOTE ]
because numbers are rigged, for more evidence see: fulltiltpoker.com

[/ QUOTE ]

Why are people trying to explain this with hexadecimals when this quote explains it entirely?

David Sklansky 11-19-2007 03:39 AM

Re: Maths: why does 987654321 / 123456789 = 8.000000073
 
I'd rather someone tell my why cubes add up to squares. Using geomety, not algebra.

mrick 11-19-2007 05:07 AM

NUMBER OF THE BEAST
 
I have worse news, sir. Try adding the numbers in ROULETTE.

1+2+3+4+...+35+36

Scary.

Dan. 11-19-2007 05:10 AM

Re: NUMBER OF THE BEAST
 
[ QUOTE ]
I have worse news, sir. Try adding the numbers in ROULETTE.

1+2+3+4+...+35+36

Scary.

[/ QUOTE ]

*GASP!*

jessica1994 11-19-2007 06:10 AM

Re: NUMBER OF THE BEAST
 
987654321/123456789 = 8.0000000729000006633900060368490...

which is very nearly 8, except for the isolated 729, 66339, 6036849 ... Now, 729 = 9^3. This isn't a coincidence, as we will see.


Explanation:
Using our prime factor finder program or built-in function, we find that:


729 = 9^3 = 9^3 * 91^0
66339 = 9^3 * 91 = 9^3 * 91^1
6036849 = 9^3 * 91^2 = 9^3 * 91^2

so we can conjecture that:


987654321/123456789 = 8 + 9^3*1E-10*SUM[N=0,N=INFINITE,(91*1E-10)^N]

where the sum goes from N=0 to N=infinite. This can be proved very easily using the well-known summation formula for geometric progressions, as this happens to be one.

john kane 11-22-2007 05:42 AM

Re: NUMBER OF THE BEAST
 
thanks for all the replies and apologies for not replying sooner. the link above has certainly helped me see there is an actual pattern, rather than it being an eerie one-off.

thanks and gl.

Duke 11-22-2007 01:17 PM

Re: Maths: why does 987654321 / 123456789 = 8.000000073
 
[ QUOTE ]
I'd rather someone tell my why cubes add up to squares. Using geomety, not algebra.

[/ QUOTE ]

I'm not convinced that they do.

pzhon 11-22-2007 05:15 PM

Re: Maths: why does 987654321 / 123456789 = 8.000000073
 
[ QUOTE ]
I'd rather someone tell my why cubes add up to squares. Using geomety, not algebra.

[/ QUOTE ]
(1+2+...+n)^2 = 1^3 + 2^3 + .. + n^3.

Proof without Words: Sum of Cubes
Alan L. Fry
Mathematics Magazine, Vol. 58, No. 1 (Jan., 1985), p. 11

I don't have that in front of me, but typically these proofs are inductive. You find some way to illustrate why n^3 = (1+2+...+n)^2-(1+2+...+(n-1))^2. If you fit the smaller square inside the larger, the remainder is an L shape, the intersection of two strips that are n x (1+2+..+n), or a strip that is n x (1+2+...+n) plus a strip that is n x (1+2+...+(n-1)). Break the strips into subrectangles indicated by the sum and pair n x k and n x (n-k), forming n pairs (pair n x n with n x 0) fitting into nxn squares.

MelchyBeau 11-22-2007 05:19 PM

Re: Maths: why does 987654321 / 123456789 = 8.000000073
 
[ QUOTE ]
[ QUOTE ]
I'd rather someone tell my why cubes add up to squares. Using geomety, not algebra.

[/ QUOTE ]

I'm not convinced that they do.

[/ QUOTE ]

he is talking about sum(i^3,i=1,k)=(sum(i,i=1,k))^2

CORed 11-25-2007 02:32 PM

Re: Maths: why does 987654321 / 123456789 = 8.000000073
 
[ QUOTE ]
Uhm.. Because 123456789 * 8 is almost equal to 987654321? Not trying to sound smug but that's all there is to it I think [img]/images/graemlins/smile.gif[/img]

[/ QUOTE ]

123456789 * 8 = 987654312, to be exact.

GoodCallYouWin 11-28-2007 02:27 AM

Re: Maths: why does 987654321 / 123456789 = 8.000000073
 
Someone is clearly trying to send us messages through the fabric of spacetime itself.


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