Comments - Indian Mathematics - TechHui2019-12-14T08:55:20Zhttp://www.techhui.com/profiles/comment/feed?attachedTo=1702911%3ABlogPost%3A38668&xn_auth=noHi Nate,
I hadn't seen those…tag:www.techhui.com,2009-04-17:1702911:Comment:400192009-04-17T17:44:14.197ZScott Murphyhttp://www.techhui.com/profile/ScottMurphy
Hi Nate,<br />
<br />
I hadn't seen those before. I look forward to your article on statistics. Numbers are always fun!<br />
<br />
Scott
Hi Nate,<br />
<br />
I hadn't seen those before. I look forward to your article on statistics. Numbers are always fun!<br />
<br />
Scott Nate Sanders: BTW, nice artic…tag:www.techhui.com,2009-04-17:1702911:Comment:400122009-04-17T15:11:32.480ZDaniel Leuckhttp://www.techhui.com/profile/dleuck
<blockquote>Nate Sanders: BTW, nice article and huge props for a math post.</blockquote>
Agreed! I think its our first.<br />
<br />
<blockquote>Nate Sanders: I'm working on an article (in my head) right now about something pertaining to statistics that I'll hopefully be able to flesh out enough to write up something here on TechHui.</blockquote>
I look forward to reading this post.
<blockquote>Nate Sanders: BTW, nice article and huge props for a math post.</blockquote>
Agreed! I think its our first.<br />
<br />
<blockquote>Nate Sanders: I'm working on an article (in my head) right now about something pertaining to statistics that I'll hopefully be able to flesh out enough to write up something here on TechHui.</blockquote>
I look forward to reading this post. BTW, nice article and huge pr…tag:www.techhui.com,2009-04-16:1702911:Comment:399332009-04-16T06:04:40.049ZNate Sandershttp://www.techhui.com/profile/NateSanders
BTW, nice article and huge props for a math post. I'm working on an article (in my head) right now about something pertaining to statistics that I'll hopefully be able to flesh out enough to write up something here on TechHui.
BTW, nice article and huge props for a math post. I'm working on an article (in my head) right now about something pertaining to statistics that I'll hopefully be able to flesh out enough to write up something here on TechHui. "Double Digit Squared" works…tag:www.techhui.com,2009-04-16:1702911:Comment:399312009-04-16T05:44:36.106ZNate Sandershttp://www.techhui.com/profile/NateSanders
"Double Digit Squared" works not only when the ones digit is 5 in both numbers, but whenever the tens digits are the same in both numbers and the sum of the ones digits is 10.<br />
<br />
23 * 27 = 2 * (2+1) | 21 = 621<br />
<br />
(10t + u)(10t + 10-u) = 100 * t * (t+1) + u(10-u) = t(t+1) | u(10-u)<br />
<br />
<br />
The multiple digit multiplication using only primitive multiplications reminds me of <a href="http://en.wikipedia.org/wiki/Napier%27s_bones">Napier's Bones</a>. I think I first saw these techniques in a book by…
"Double Digit Squared" works not only when the ones digit is 5 in both numbers, but whenever the tens digits are the same in both numbers and the sum of the ones digits is 10.<br />
<br />
23 * 27 = 2 * (2+1) | 21 = 621<br />
<br />
(10t + u)(10t + 10-u) = 100 * t * (t+1) + u(10-u) = t(t+1) | u(10-u)<br />
<br />
<br />
The multiple digit multiplication using only primitive multiplications reminds me of <a href="http://en.wikipedia.org/wiki/Napier%27s_bones">Napier's Bones</a>. I think I first saw these techniques in a book by <a href="http://en.wikipedia.org/wiki/Shakuntala_Devi">Shakuntala Devi</a> a long time ago, though, and there are definitely plenty of diagrams in her book for fast multiplication. BTW, I think this is normally called "Vedic Math".<br />
<br />
At a higher level, I remember feeling a good bit of awe when I was introduced to <a href="http://en.wikipedia.org/wiki/Strassen_algorithm">Strassen's Method for Matrix Multiplication</a>. He basically figured this out by writing out the dot products involved in a matrix multiplication and factoring out common pieces to cause fewer multiplies and more adds (multiplies were a lot costlier then than they are now).