Mathman or any other math experts...

[sk8guy2k2]

Mathman or any other math experts...

Do you guys know any websites with the history of percentages or know about percentages? I'm writing a report on percentages-history, descriptions, everyday and career applications...stuff like that. I have gathered info here and there on it. It's hard to find the history of percentages with Yahoo and search engines. Any info will be GREATLY appreciated.

 

[mathman444]

Re: Mathman or any other math experts...

Gosh, the history of per cents. Does your report have to be on this topic, or do you have a choice? Here are a bunch of cool topics in mathematics that actually have a legitimate and fully fledged "history:"

www-gap.dcs.st-and.ac.uk/..._alph.html

The trouble with per cents [aside -- if you want to do a search for educational materials about how to teach this subject to children it seems to be best to spell it this way, "percent," instead of "per cent." -- I don't know why. Perhaps for the same reason (i.e., none) that computer scientists always pervesely mispronounce the word "data." Or at least they used to, before the character on Star Trek II taught a whole generation of children how to say it.]

The trouble with "the history of per cents" is that every culture that uses a base ten numbering system (this includes most -- but not all (!) -- societies whose members have 10 fingers), and which has enough mathematical moxie to think of the idea of ratio and proportion (again, almost everybody), will come naturally to the idea of per cent as the ratio of some number of objects to 100. If you are a Centurian but the legion under your command has only 3/4 its normal complement, how many soldiers do you have?

So I don't think that you will be able to say anything along the lines of, "the concept of percentage was invented by the Kmet civilization of the upper Nile in the fourth dynasty, under the leadership of the scribe Ahmenhotep," or anything like that.

Now I feel like I let you down. Ask me something else.

Mathman

 

[sk8guy2k2]

Re: Mathman or any other math experts...

Thanks anyway...now I don't want to do percents, maybe I'll do something about pi now...

 

[mathman444]

Re: Mathman or any other math experts...

Now you have the opposite problem -- an overabundance of resources. Two very complete summaries are "The History of Pi" by David Blatner and "The Joy of Pi" by Peter Beckman. Also, as I'm sure you've discovered, just type "History of Pi" into your search engine and you get thousands of hits, lots of them of quality.

Here's an interesting summary of attempts to calculate pi from antiquity to now.

www.cecm.sfu.ca/projects/...story.html

Did you know that you can use Pi to measure the curvature of the universe? (And I mean for real -- this is what astronomers actually do -- not just in theory). If we define Pi to be the ratio of the circumference to the diameter of the circle, then the usual constant Pi that we calculate, Pi = 3.14159..., means that ratio for circles drawn in the flat Euclidean plane.

In a space of positive curvature, the ratio C/D is less than this value, and increasingly less and less as the size of the circle gets bigger. In a negatively curved space, the ratio C/D is larger than this Euclidean vaule of 3.14159....

The formulas relating the Circumference, the Radius, the Cuvature (k), and the Euclidean value of Pi (P) are:

C = 2pr (flat surface)

C =(2p/k)*sin(kr) (surface of positive curvature)

C = (2p/k)*sinh(kr) (surface of negative curvature)

"sin" is the ordinary trigonometric sine function and "sinh" is the "hyperboic sine" function.

So all we have to do to find out if we live in a falt universe or in a universe of negative or positive curvature is to draw a big circle in the sky, measure its circumference and diameter, and see which formula gives the best fit.

Astronomers can estimate the radius by red shift and the circumference by observing density of galaxy clusters.

Say that in your report -- it'll blow your Prof away.:lol:

Mathman

PS. Your signature is funny to me because I often have to do exactly that. I have a slight visual handicap that makes me nervous about turning left. So sometimes I do make three rights.

 

[sk8guy2k2]

Re: Mathman or any other math experts...

Thanks Mathman! Wow! I didn't know that. I think I'll add that in...