Obviously I an NOT as smart as a 6th grader - MATH HELP (Page 2)

Why?

The ancient Greeks, Chinese, Indians, and Persians, among others, used this approximation or its rough equivalent with great success for thousands of years.  I say if it was good enough for Archimedes, it is good enough for me.

You let me know when you find the real value.  Last I checked, mathmagicians were still looking for it.  They were at a trillion digits and still counting.

You sound like my 9 year old, who hates to estimate.  I have told him that EVERYTHING is an estimate.  The only question is how precise you want to be.

Don't be so square minded. You know what I meant for "real."

3.141592 is a better approximation than 3.142857.

It is fine to estimate "1 cup of sugar" for your super pie recipe. It is not fine to estimate (or, so you understand, estimate with the less margin of error possible) if you are building a bridge, designing a building, launching a rocket, etc.

Edit:

Thanks, Shane. For saying what I wanted to say in a more eloquent and classy way.

The OP's question was related to the diameter of a bicycle wheel, not launching a rocket.

Using 22/7 would be more than sufficiently precise, as it would already give you an answer that would be beyond the precision of any common measuring device.

When launching a rocket, 3.141592 would not be sufficiently precise.

Now you are just arguing for the sake of arguing.

Error analysis theory says to use only the number of significant figures that your least accurate data point is.  Measurement in this case is limited by the accuracy of your yard stick, or what ever device is used to measure the distance.

It's amazing how many people don't even know what "pi" is.  If you ask people what pi is they always say 3.14, and if you ask them why is it 3.14 and how do they come up with that you get a blank stare.

Pi is the ratio of the circumference of a circle to its diameter.  (C/d)

The OP's question was related to the diameter of a bicycle wheel, not launching a rocket.

Using 22/7 would be more than sufficiently precise, as it would already give you an answer that would be beyond the precision of any common measuring device.

When launching a rocket, 3.141592 would not be sufficiently precise.

Ya know, you really could have saved the Dear Leader or Great Fearless Courageous Leader (or whatever they're calling Kim Jong-un these days) a lot of trouble if you had let him know this fact, because I'm pretty sure they used 22/7 for this latest rocket launch of theirs.

^^ Heh heh Score!!!

Error analysis theory says to use only the number of significant figures that your least accurate data point is.  Measurement in this case is limited by the accuracy of your yard stick, or what ever device is used to measure the distance.

But Pi is not a data point.  It's an irrational constant.