Drexel dragonThe Math ForumDonate to the Math Forum

Ask Dr. Math - Questions and Answers from our Archives
_____________________________________________
Associated Topics || Dr. Math Home || Search Dr. Math
_____________________________________________

Remembering Pi


Date: 08/27/2001 at 22:34:12
From: Paul
Subject: An easy way of getting to Pi

I would like to find out two things:

1) Is there an easy way of finding Pi, only to 3.141592654, that is 
memorizable and not too confusing? I memorized 3.14 a long time ago, 
but for when I am not using a scientific calculator, is there an easy 
way to get i? I already know 22/7, but that is off by 0.00126. 

2) Why did I learn in fifth grade that pi was 3.14285714?

Thank you for your time and effort!


Date: 08/28/2001 at 09:26:40
From: Doctor Peterson
Subject: Re: An easy way of getting to Pi

Hi, Paul.

Ten digits are perfectly possible to memorize; people have gone a lot 
farther. I myself use 3.14159, which is more than enough for most 
purposes.

3.14285714 is 22/7 to eight decimal places; you must have thought that 
was actually equal to pi. Just unlearn what you learned in fifth grade 
and replace it with the right value.

Another well-known approximation, which is quite easy to memorize, is 
355/113; this equals 3.14159292... and is as good as the decimal I 
use. 

Note that the odd numbers 1, 3, and 5 appear twice each, in a simple 
pattern: 113,355, denominator first. Nothing could be much easier than 
that!

- Doctor Peterson, The Math Forum
  http://mathforum.org/dr.math/   
    
Associated Topics:
Middle School Pi

Search the Dr. Math Library:


Find items containing (put spaces between keywords):
 
Click only once for faster results:

[ Choose "whole words" when searching for a word like age.]

all keywords, in any order at least one, that exact phrase
parts of words whole words

Submit your own question to Dr. Math

[Privacy Policy] [Terms of Use]

_____________________________________
Math Forum Home || Math Library || Quick Reference || Math Forum Search
_____________________________________

Ask Dr. MathTM
© 1994-2013 The Math Forum
http://mathforum.org/dr.math/