How to get PI without the PI key?

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In summary, the conversation is about different methods for obtaining the value of pi on a calculator, including using trigonometric functions, memorization, and mathematical approximations. Some suggestions include using the BA II plus Prof. calculator's "math.e" function, using mnemonic methods, and using the formula "Pi=sin(dalpha)*180/dalpha" for degrees.
  • #1
chocok
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Hi, I have a BA II plus Prof. and there's no "pi" key, I tried using the trig functions to get the value but it always give me a something in degrees.

I want to avoid using 22/7 as it's not close enough.
Is there any way to get the number instead of memorizing it?

THanks!
 
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  • #2
How about 31415/10000?
 
  • #3
Well, memorizing it to 5 or so digits isn't that hard (I know 15 just in case =] ) and in fact it may be easier to remember than any other method of getting the number on your calculator. I could tell you [tex]\pi \approx \frac{ \log_e ( 640320^3 + 744)}{\sqrt{163}}[/tex], which is accurate to around 70 digits, but that's much harder to memorize, not to mention if the button doesn't have pi, it probably won't have the other functions. Either remember, 3.1415926535 (truncate it earlier if you want) or, even better, 355/113 is good to 7 or so digits.
 
  • #4
chocok said:
Hi, I have a BA II plus Prof. and there's no "pi" key, I tried using the trig functions to get the value but it always give me a something in degrees.
What's a BA II plus Prof.? I'm going to assume a scientific calculator... most calculators allow you to switch the trig mode between degrees, radians, and gradians.
 
  • #5
Here is a link to the TI webpage where you can download a manual:
http://education.ti.com/educationportal/downloadcenter/SoftwareDetail.do?website=US&tabId=2&appId=6114
 
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  • #6
Guys, I think he's looking for a way to write out PI itself without approximating it by whole number division or some other mathematical trick. Meaning to say that he wants to be able to write out PI with some mathematical expression as an number with an infinite decimal places accurately to any precision he wishes. (sorry if I sound a little incoherent, I'm down with fever at present)

Why not try PI as the sum to infinity of some series?

Like:

http://en.wikipedia.org/wiki/Leibniz_formula_for_pi

Or this:
http://www.geom.uiuc.edu/~huberty/math5337/groupe/expresspi.html
http://en.wikipedia.org/wiki/Computing_π
 
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  • #7
Do you mean through a simple calculation to obtain a good or comfortable approximation? Try either memorizing the first six digits, or use a mnemonic method. Try an internet search and you can find something that goes like, "Hey, I need a drink..."; I forgot how the rest of it goes, but count the letters in each word, use the comma as a decimal point, and you find 3.1415...

Then there is the simple calculation, 1 1 3 3 5 5 arrangement which uses the ratio 355/113
 
  • #8
What about 2 * Arcsin (1)?
 
  • #9
This might help:

http://www.isi.edu/~johnh/ABOUT/FEATURES/RATIONAL_PI/index.html"

Those are rational approximations of Pi up to a tolerance of 2.6621325721620792e-07.
 
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  • #10
Defennnder said:
Guys, I think he's looking for a way to write out PI itself without approximating it by whole number division or some other mathematical trick. Meaning to say that he wants to be able to write out PI with some mathematical expression as an number with an infinite decimal places accurately to any precision he wishes.
I don't, I think he is just looking for a way to use "[itex]\pi[/itex]" on his calculator!
Unfortunately, he hasn't gotten back to us so we can't be sure what he wants.

The BA II calculator is itself a "financial" calculator and is, apparently, "object oriented" since the manual talks about "objects" that may or may not have "constructors" and have values of functions accessed by a ".". In particular, Chocok, "MATH.E" gives you the value of "e".
You can find it in your manual, I think on pages 95- 100. If you don't still have the manual, you can find a PDF copy at the website I posted before but here it is again:
http://education.ti.com/educationportal/sites/US/productDetail/us_baii_plus.html?bid=6
 
  • #11
Diffy said:
What about 2 * Arcsin (1)?

This works if trig. functions are defined in radians, not in degrees. In the later case I would use the formula:

sin(dfi)=dfi (radians)

Consequence:

sin(dalpha)=dalpha*2*Pi/360 (degrees)

So: Pi=sin(dalpha)*180/dalpha
 

1. How can I obtain PI without the PI key?

Unfortunately, it is not possible to obtain PI without the PI key. The key is a unique identifier that is required for accessing PI, and it is typically only given to individuals who have a legitimate need for it, such as researchers and scientists.

2. Is there a way to bypass the need for a PI key?

No, there is no way to bypass the need for a PI key. It is a necessary security measure in order to protect the sensitive information contained within PI.

3. Can I purchase a PI key from someone else?

No, PI keys are not transferable and cannot be purchased from someone else. Each key is assigned to a specific individual and cannot be shared or sold.

4. What should I do if I have lost my PI key?

If you have lost your PI key, you should contact the organization or institution that issued the key to you. They will be able to provide you with a replacement key or assist you in retrieving your lost key.

5. Can I use someone else's PI key for my research?

No, you should never use someone else's PI key for your research. This is a violation of privacy and can lead to serious consequences. Each individual must have their own PI key in order to access the information.

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