Weird Maths

Free, open, general chat on any topic.

Moderators: Orlion, balon!, aliantha

User avatar
stonemaybe
The Gap Into Spam
Posts: 4836
Joined: Mon Feb 20, 2006 9:37 am
Location: Wallowing in the Zider Zee

Weird Maths

Post by stonemaybe »

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! :D

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

(:/>
User avatar
Waddley
The Gap Into Spam
Posts: 2406
Joined: Wed May 17, 2006 10:37 pm
Location: Titan Moon Best Moon
Contact:

Post by Waddley »

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
"Let my inspiration flow in token rhyme, suggesting rhythm." -Robert Hunter
User avatar
stonemaybe
The Gap Into Spam
Posts: 4836
Joined: Mon Feb 20, 2006 9:37 am
Location: Wallowing in the Zider Zee

Post by stonemaybe »

I also love this method, which is apparently taught in China:
www.youtube.com/watch?v=VBsC0p9mHPs
OMG 8O :lol:



Edit: mine's was described in a newspaper yesterday
Aglithophile and conniptionist and spectacular moonbow beholder 16Jul11

(:/>
User avatar
Rigel
The Gap Into Spam
Posts: 2096
Joined: Wed Sep 26, 2007 10:42 pm
Location: Albuquerque

Re: Weird Maths

Post by Rigel »

Stonemaybe 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.
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 apparent :)
"You make me think Hell is run like a corporation."
"It's the other way around, but yes."
Obaki, Too Much Information
User avatar
Avatar
Immanentizing The Eschaton
Posts: 61791
Joined: Mon Aug 02, 2004 9:17 am
Location: Johannesburg, South Africa
Has thanked: 15 times
Been thanked: 22 times

Post by Avatar »

Uh...yeah...I can barely do math the easy way... :lol:

--A
User avatar
Vraith
The Gap Into Spam
Posts: 10621
Joined: Fri Nov 21, 2008 8:03 pm
Location: everywhere, all the time

Post by Vraith »

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.
User avatar
stonemaybe
The Gap Into Spam
Posts: 4836
Joined: Mon Feb 20, 2006 9:37 am
Location: Wallowing in the Zider Zee

Post by stonemaybe »

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]
I vaguely remember a method to find out which months have 30days by counting knuckles, but can't remember it....
Aglithophile and conniptionist and spectacular moonbow beholder 16Jul11

(:/>
User avatar
Vader
The Gap Into Spam
Posts: 1865
Joined: Sun Jan 04, 2009 4:03 pm
Location: On the lam
Been thanked: 2 times
Contact:

Post by Vader »

Mathematics can be mind boggling. Fantastic post.
Stonemaybe wrote:I vaguely remember a method to find out which months have 30days by counting knuckles, but can't remember it....
Count knuckles and spaces between.

Image
Functionless art is vandalism. I am the vandal.
User avatar
Fist and Faith
Magister Vitae
Posts: 23741
Joined: Sun Dec 01, 2002 8:14 pm
Has thanked: 7 times
Been thanked: 34 times

Post by Fist and Faith »

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]
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.
All lies and jest
Still a man hears what he wants to hear
And disregards the rest
-Paul Simon
User avatar
Phantasm
The Gap Into Spam
Posts: 1720
Joined: Sun Jul 03, 2005 10:52 pm
Location: Cumbernauld, Scotland

Post by Phantasm »

Isn't that what calculators are for?
Quote - John Smeaton (Terrorists take note)

"This is Glasgow- we'll just set aboot ye"



Image
User avatar
Vraith
The Gap Into Spam
Posts: 10621
Joined: Fri Nov 21, 2008 8:03 pm
Location: everywhere, all the time

Post by Vraith »

Fist and Faith wrote:
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]
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.
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...
[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.
User avatar
stonemaybe
The Gap Into Spam
Posts: 4836
Joined: Mon Feb 20, 2006 9:37 am
Location: Wallowing in the Zider Zee

Post by stonemaybe »

come on then, spill the beans!
Aglithophile and conniptionist and spectacular moonbow beholder 16Jul11

(:/>
User avatar
Vraith
The Gap Into Spam
Posts: 10621
Joined: Fri Nov 21, 2008 8:03 pm
Location: everywhere, all the time

Post by Vraith »

Me? Heh, I wasn't trying to be mysterious: here's one of them:

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.
User avatar
stonemaybe
The Gap Into Spam
Posts: 4836
Joined: Mon Feb 20, 2006 9:37 am
Location: Wallowing in the Zider Zee

Post by stonemaybe »

Vraith wrote:Me? Heh, I wasn't trying to be mysterious: here's one of them:

gwydir.demon.co.uk/jo/numbers/finger/multiply.htm
I like!

It is easier, however, just to have had the times tables drummed into you as a kid!
Aglithophile and conniptionist and spectacular moonbow beholder 16Jul11

(:/>
User avatar
hierachy
Lord
Posts: 4813
Joined: Tue Sep 16, 2003 10:20 pm

Post by hierachy »

Cool stuff! :D
User avatar
matrixman
The Gap Into Spam
Posts: 8361
Joined: Thu Jul 10, 2003 11:24 am

Post by matrixman »

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. :wink:
I think I'll stick with the way I learned it in school here, thanks. :lol:
(Basic math, the ABC's, and typing -- the only useful learning I got out of school, but that's another topic.)
User avatar
stonemaybe
The Gap Into Spam
Posts: 4836
Joined: Mon Feb 20, 2006 9:37 am
Location: Wallowing in the Zider Zee

Post by stonemaybe »

(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?
Aglithophile and conniptionist and spectacular moonbow beholder 16Jul11

(:/>
User avatar
Vraith
The Gap Into Spam
Posts: 10621
Joined: Fri Nov 21, 2008 8:03 pm
Location: everywhere, all the time

Post by Vraith »

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:
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.
User avatar
stonemaybe
The Gap Into Spam
Posts: 4836
Joined: Mon Feb 20, 2006 9:37 am
Location: Wallowing in the Zider Zee

Post by stonemaybe »

A Curious Incident = Mark Haddon's novel 'The Curious Incident of the Dog in the Night-time'.
Spoiler
Correct answer! If you switch, you are twice as likely to win the car!
Aglithophile and conniptionist and spectacular moonbow beholder 16Jul11

(:/>
User avatar
Shuram Gudatetris
<i>Haruchai</i>
Posts: 683
Joined: Wed Dec 20, 2006 8:48 pm
Location: Cameron, Missouri
Contact:

Post by Shuram Gudatetris »

I have heard this said on a movie once, but I don't understand the reasoning behind it. What is the logical explanation?
Covenant is Linden Frankenstein's monster.

I maxed-out Tetris!
Post Reply

Return to “General Discussion Forum”