Weird Maths
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- stonemaybe
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Weird Maths
I learnt how the ancient Egyptians used to multiply yesterday. I thought my delight in numbers was long gone, but this brought it all back!
Take the two numbers that you want to multiply and write them down side by side. Double the one on the left and write that number beneath. Halve the one on the right and write that beneath the number just halved. ie
65.......86
130.....43
Keep doing this, doubling the one on the left, and halving the one on the right. If the number on the right is odd, like 43 above, put a * next to it, and when you halve it, forget about any fractional remainder. Keep doing this until the number on the right is 1 (which you'll also put a * beside, because it's odd). You end up with....
65............86
130..........43*
260..........21*
520..........10
1040..........5*
2080..........2
4160..........1*
Now add the numbers in the left hand column, but only the ones where there is a star on that line, so 130 + 260 + 1040 + 4160 = 5590, which is what you get when you multiply 65 by 86.
Ta da!
You have just, apparently, broke these number down into base two (binary), to do multiplication the different way.
Take the two numbers that you want to multiply and write them down side by side. Double the one on the left and write that number beneath. Halve the one on the right and write that beneath the number just halved. ie
65.......86
130.....43
Keep doing this, doubling the one on the left, and halving the one on the right. If the number on the right is odd, like 43 above, put a * next to it, and when you halve it, forget about any fractional remainder. Keep doing this until the number on the right is 1 (which you'll also put a * beside, because it's odd). You end up with....
65............86
130..........43*
260..........21*
520..........10
1040..........5*
2080..........2
4160..........1*
Now add the numbers in the left hand column, but only the ones where there is a star on that line, so 130 + 260 + 1040 + 4160 = 5590, which is what you get when you multiply 65 by 86.
Ta da!
You have just, apparently, broke these number down into base two (binary), to do multiplication the different way.
Aglithophile and conniptionist and spectacular moonbow beholder 16Jul11
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- Waddley
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That's really great, I'm going to try and remember it. Where did you learn it?
I also love this method, which is apparently taught in China:
www.youtube.com/watch?v=VBsC0p9mHPs
I also love this method, which is apparently taught in China:
www.youtube.com/watch?v=VBsC0p9mHPs
"Let my inspiration flow in token rhyme, suggesting rhythm." -Robert Hunter
- stonemaybe
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OMGI also love this method, which is apparently taught in China:
www.youtube.com/watch?v=VBsC0p9mHPs
Edit: mine's was described in a newspaper yesterday
Aglithophile and conniptionist and spectacular moonbow beholder 16Jul11
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Re: Weird Maths
Pretty cool... read down the far right side, put a "0" for no star and a "1" for a star, and the binary connection becomes much more apparentStonemaybe wrote: 65............86
130..........43*
260..........21*
520..........10
1040..........5*
2080..........2
4160..........1*
...
You have just, apparently, broke these number down into base two (binary), to do multiplication the different way.
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- Vraith
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There's an easy way to do basic math with your fingers...anyone ever seen that? [heh...I don't mean counting...that would be silly]
[spoiler]Sig-man, Libtard, Stupid piece of shit. change your text color to brown. Mr. Reliable, bullshit-slinging liarFucker-user.[/spoiler]
the difference between evidence and sources: whether they come from the horse's mouth or a horse's ass.
"Most people are other people. Their thoughts are someone else's opinions, their lives a mimicry, their passions a quotation."
the hyperbole is a beauty...for we are then allowed to say a little more than the truth...and language is more efficient when it goes beyond reality than when it stops short of it.
the difference between evidence and sources: whether they come from the horse's mouth or a horse's ass.
"Most people are other people. Their thoughts are someone else's opinions, their lives a mimicry, their passions a quotation."
the hyperbole is a beauty...for we are then allowed to say a little more than the truth...and language is more efficient when it goes beyond reality than when it stops short of it.
- stonemaybe
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I vaguely remember a method to find out which months have 30days by counting knuckles, but can't remember it....There's an easy way to do basic math with your fingers...anyone ever seen that? [heh...I don't mean counting...that would be silly]
Aglithophile and conniptionist and spectacular moonbow beholder 16Jul11
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- Fist and Faith
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On Northern Exposure, Holling knew how. That's the only time I've ever heard of it. I didn't assume it was a real thing, though.Vraith wrote:There's an easy way to do basic math with your fingers...anyone ever seen that? [heh...I don't mean counting...that would be silly]
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And disregards the rest -Paul Simon
Still a man hears what he wants to hear
And disregards the rest -Paul Simon
- Vraith
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Wow...I completely forgot that about him! I did some searching around, there are actually several methods, most of them you have to be able to multiply up to 4 in your head, there are 2 for doing x5-x10, and a different one for any number...Fist and Faith wrote:On Northern Exposure, Holling knew how. That's the only time I've ever heard of it. I didn't assume it was a real thing, though.Vraith wrote:There's an easy way to do basic math with your fingers...anyone ever seen that? [heh...I don't mean counting...that would be silly]
[spoiler]Sig-man, Libtard, Stupid piece of shit. change your text color to brown. Mr. Reliable, bullshit-slinging liarFucker-user.[/spoiler]
the difference between evidence and sources: whether they come from the horse's mouth or a horse's ass.
"Most people are other people. Their thoughts are someone else's opinions, their lives a mimicry, their passions a quotation."
the hyperbole is a beauty...for we are then allowed to say a little more than the truth...and language is more efficient when it goes beyond reality than when it stops short of it.
the difference between evidence and sources: whether they come from the horse's mouth or a horse's ass.
"Most people are other people. Their thoughts are someone else's opinions, their lives a mimicry, their passions a quotation."
the hyperbole is a beauty...for we are then allowed to say a little more than the truth...and language is more efficient when it goes beyond reality than when it stops short of it.
- stonemaybe
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- Vraith
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Me? Heh, I wasn't trying to be mysterious: here's one of them:
gwydir.demon.co.uk/jo/numbers/finger/multiply.htm
gwydir.demon.co.uk/jo/numbers/finger/multiply.htm
[spoiler]Sig-man, Libtard, Stupid piece of shit. change your text color to brown. Mr. Reliable, bullshit-slinging liarFucker-user.[/spoiler]
the difference between evidence and sources: whether they come from the horse's mouth or a horse's ass.
"Most people are other people. Their thoughts are someone else's opinions, their lives a mimicry, their passions a quotation."
the hyperbole is a beauty...for we are then allowed to say a little more than the truth...and language is more efficient when it goes beyond reality than when it stops short of it.
the difference between evidence and sources: whether they come from the horse's mouth or a horse's ass.
"Most people are other people. Their thoughts are someone else's opinions, their lives a mimicry, their passions a quotation."
the hyperbole is a beauty...for we are then allowed to say a little more than the truth...and language is more efficient when it goes beyond reality than when it stops short of it.
- stonemaybe
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Fascinating topic, Stone!
Never knew about that Chinese method either. Thanks, Waddley!
Have to say, they look like the Rube Goldberg way of doing multiplication.
I think I'll stick with the way I learned it in school here, thanks.
(Basic math, the ABC's, and typing -- the only useful learning I got out of school, but that's another topic.)
Never knew about that Chinese method either. Thanks, Waddley!
Have to say, they look like the Rube Goldberg way of doing multiplication.
I think I'll stick with the way I learned it in school here, thanks.
(Basic math, the ABC's, and typing -- the only useful learning I got out of school, but that's another topic.)
- stonemaybe
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(this question is out of bounds to anyone who has read 'A Curious Incident....')
You are on a game show on television. On this game show the idea is to win a car as a prize. The game show host shows you three doors. He says that there is a car behind one of the doors and there are goats behind the other two doors. He asks you to pick a door. You pick a door but the door is not opened. Then the game show host opens one of the doors you didn't pick to show a goat (because he knows what is behind each door). Then he says you have one final chance to change your mind before the doors are opened and you get a car or a goat. So he asks you if you want to change your mind and pick the other unopened door instead. What should you do?
You are on a game show on television. On this game show the idea is to win a car as a prize. The game show host shows you three doors. He says that there is a car behind one of the doors and there are goats behind the other two doors. He asks you to pick a door. You pick a door but the door is not opened. Then the game show host opens one of the doors you didn't pick to show a goat (because he knows what is behind each door). Then he says you have one final chance to change your mind before the doors are opened and you get a car or a goat. So he asks you if you want to change your mind and pick the other unopened door instead. What should you do?
Aglithophile and conniptionist and spectacular moonbow beholder 16Jul11
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- Vraith
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What's "A Curious Incident...?" sounds like one of those Lemony Sniksomething books....
Anyway I think, if I recall the math correctly the answer would be:
Anyway I think, if I recall the math correctly the answer would be:
Spoiler
Better odds of winning car if you switch.
[spoiler]Sig-man, Libtard, Stupid piece of shit. change your text color to brown. Mr. Reliable, bullshit-slinging liarFucker-user.[/spoiler]
the difference between evidence and sources: whether they come from the horse's mouth or a horse's ass.
"Most people are other people. Their thoughts are someone else's opinions, their lives a mimicry, their passions a quotation."
the hyperbole is a beauty...for we are then allowed to say a little more than the truth...and language is more efficient when it goes beyond reality than when it stops short of it.
the difference between evidence and sources: whether they come from the horse's mouth or a horse's ass.
"Most people are other people. Their thoughts are someone else's opinions, their lives a mimicry, their passions a quotation."
the hyperbole is a beauty...for we are then allowed to say a little more than the truth...and language is more efficient when it goes beyond reality than when it stops short of it.
- stonemaybe
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