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#1 2007-07-27 09:55:56
- Math_Girl
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- Registered: 2007-07-27
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Useful Multiplacation "trick"
This has been of great help to me and i now can do this method in my head. It's hard to explain so i'll let the video exlplain
http://www.youtube.com/watch?v=YFvwRzjTWAw
Last edited by Math_Girl (2007-07-27 09:56:49)
"Genius is 1% inspiration and 99% determination"
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#2 2007-07-27 10:16:34
- mikau
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Re: Useful Multiplacation "trick"
thats neat. i like how you can do it without all that obxnoxious collumn addition. Still, i quickly loose track of numbers when i hold them in my head which is why i need to write stuff down. 
you must have a good memory.
Last edited by mikau (2007-07-27 10:16:50)
A logarithm is just a misspelled algorithm.
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#3 2007-07-27 10:21:10
- Math_Girl
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Re: Useful Multiplacation "trick"
How else do you think i learnt 765 digits of pi? 
"Genius is 1% inspiration and 99% determination"
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#4 2007-07-27 13:57:23
- MathsIsFun
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Re: Useful Multiplacation "trick"
That's a lot of pi!
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman
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#5 2007-07-27 20:20:56
- Math_Girl
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Re: Useful Multiplacation "trick"
It is indeed and it's very delicious
"Genius is 1% inspiration and 99% determination"
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#6 2007-07-27 20:34:36
- luca-deltodesco
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- Registered: 2006-05-05
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Re: Useful Multiplacation "trick"
never though of doing it like that 
and it makes perfect sense aswell
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The End Of All Things To Come.
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#7 2007-07-30 11:37:39
- mpthomas
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Re: Useful Multiplacation "trick"
How else do you think i learnt 765 digits of pi?
Why?
Why on earth?
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#8 2007-07-31 01:30:43
- Math_Girl
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Re: Useful Multiplacation "trick"
Well, why not?
I did it to help improve my memory. Plus i was bored and the place i was staying at happened to have a poster of pi.
"Genius is 1% inspiration and 99% determination"
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#9 2007-07-31 12:49:00
- mpthomas
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Re: Useful Multiplacation "trick"
Hehe - congratulations. It actually sounds like some crazy sheet I would do.
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#10 2007-08-05 17:13:57
- George,Y
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- Registered: 2006-03-12
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Re: Useful Multiplacation "trick"
(10a+b)(10c+d)= bd+10(ac+bd)+100ac
is the principle.
A good way! At least it's easier than the conventional way.
X'(y-Xβ)=0
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#11 2007-08-05 17:23:35
- George,Y
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Re: Useful Multiplacation "trick"
I mean, it doesn't require the intermediate storage so much.
like 23*36 you have to bear in mind 23*3 and 23*6 but now only 1 from 18 (1*10) , 9, 12,
then 2 from 22.
828, correct!
However, it cannot simplify 238*36 too much.
X'(y-Xβ)=0
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