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If everyone liked and was amazed by the "DON'T CHEAT YOUR AGE BY SEX" thread that i posted. I just received one that will top it.

I'm listening if anyone can tell me how this works?????

http://www.mysticalball.com/ :eek:oo: :eek:oo: :eek:oo: :eek:oo: They didn't predict the tsunami. :bawling:
 

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the answer is always 9 or a multiple of 9


99 18 gives 81
88 16 gives 72

87 15 gives 72
5x gives 45
4x gives 36
etc etc etc

all multiples of 9 have the same symbol, click and that symbol changes. but all multiples of 9 have the same smybol still
 

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Gross.

I guess sheer calculation power- but there must be a system.

You can group several combinations which always have the same result.
e.g. 13: 13-4=9
15: 15-6=9
Next one is 18, next one 27... see the system?

Ok, now why?

Take 23 and 32: one result is 18, the other one 27.

The 20.29s:
20: 2 kept steady. you always substract 2.
now oh wonder. 20 - 2 = 18.
add anything to 20, like 5: you also add it to what you substract. so even at 29 you calculate:
29 - 11 = 18.

so at the 30s you calculate:
3x-(3+x)
which is 3*10 + x*1 -3 -x = 30 -3 +x -x = 27.

wohoo, got the system.
so the last part is:
why is x*10 - x = 9*x?
well, except knowing the little x*9 and see it you can do prove it by complete induction:

assume that x*10 - x = 9 * x

start with x = 1:
1 * 10 - 1 = 10-1 = 9 = 9 * 1 True

continue with x-> x+1:
(x+1) *10 - (x+1) = (x+1)*9. True.

That means: this rule is true for all numbers!!!

E.g. be x = 1774:
1774 * 10 = 17740 - 1774 = 15966 = 9 * 1774

Hooray.
And the last line of my little proof explains also why:
10*x is x+x+x+x+x+x+x+x+x+x (10 times)
when you substract one x you get:
x+x+x+x+x+x+x+x+x (9 times) which is 9*x

:tongue:
 

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Argh, I should just have written what WingsWheels said.
But now you should also know WHY its a multiple of 9 :grin:
 

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In short, the system is:

x,y := 1..9
xy = x*10 + y

xy - (x+y) = x*10 - x +y -y = x*10 -x = x*9

That means y doesn't affect the result, which is always the first digit times 9.
 

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man, it took me longer to write my answer then to figure out the system

it must have taken you about an hour to write that, and 10 seconds to think it up. Im far to lazy to explain the theory behind it :lol:
 

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[ QUOTE ]
wingswheels said:
the answer is always 9 or a multiple of 9


99 18 gives 81
88 16 gives 72

87 15 gives 72
5x gives 45
4x gives 36
etc etc etc

all multiples of 9 have the same symbol, click and that symbol changes. but all multiples of 9 have the same smybol still

[/ QUOTE ]

Basically what I said in a somewhat less technical way.
 

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looking at what you said, you're right, but in a far less technical way then SS's thesis
 

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Ok, never mind. I didnt realize that the symbols next to the numbers changed every time you reset it so it would work. My bust. Damn, what do colleges teach kids these days that they can get a 3.75 and not get this...
 
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