Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » sci.math.* » sci.math.independent

Topic: Great Math Tricks on youtube
Replies: 8   Last Post: Jan 1, 2014 9:36 AM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Thomas Nordhaus

Posts: 433
Registered: 12/13/04
Re: Great Math Tricks on youtube
Posted: Jan 1, 2014 9:36 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

Am 01.01.2014 01:31, schrieb Christopher J. Henrich:
> In article <79fe4482-109f-4177-b73a-eee98fa1dff8@googlegroups.com>,
> christian.bau <christian.bau@cbau.wanadoo.co.uk> wrote:
>

>> On Monday, December 30, 2013 8:37:29 AM UTC, Phil Carmody wrote:
>>> Today I learnt that
>>>
>>> 11.5 / 2 = 6.725
>>>
>>> Teach me more of these internet things called "math tricks"!

>>
>> Sad that the guy is really bad at mental arithmetic.
>>
>> Apart from that, he tells us that to solve (1 + p / 100)^n = 2 for n we let n
>> = 72 / p,

> A better approximation is 69/p, based on ln(2) = 0.693...

Of course this is a better approximation for very small values of p, but
they are not of very high interest for an investor ;) For values of p
between let's say p=5% and p=20% the 72-rule seems to work better.

--
Thomas Nordhaus




Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.