At which scale (real world day to day life situation) when each extra digit of pi become necessary?
g6d3np81@kbin.social to 
xkcd: Coordinate Precision but pi (π)?
I tried looking for some answer but found mostly
- People reciting pi
- People teaching how to memorize pi
- How to calculate pi using different formula
- How many digits NASA uses
Update question to be more specific
In case someone see this later, what is the most advanced object you can build or perform its task, with different length of pi?
0, 3 => you can't make a full circle
1, 3.1 => very wobbly circle
2, 3.14 => perfect hole on a beach
3, 3.142 => ??
4, 3.1416 => ??
5, 3.14159 => ??
Old question below
In practice, the majority of people will never require any extra digit past 3.14. Some engineering may go to 3.1416. And unless you are doing space stuff 3.14159 is probably more than sufficient.
But at which point do a situation require extra digit?
From 3 to 3.1 to 3.14 and so on.My non-existing rubber duck told me I can just plug these into a graphing calculator. facepalm
y=(2πx−(2·3.14x))
y=abs(2πx−(2·3.142x))
y=abs(2πx−(2·3.1416x))
y=(2πx−(2·3.14159x))
Got adequate answer from @dual_sport_dork and @howrar
Any extra example of big object and its minimum pi approximation still welcome.
Significant Figures: am I a joke to you?
Accurate(closer to the real answer), is not equal to precise(consistent measurements). I think… right?
Yes. I had a science teacher devote a significant portion of a day’s lecture to that exact subject: the difference between accuracy and precision. You got it right.
For example, if you have a digital scale that displays weight to five decimal points, it’s precise. If that scale hasn’t been properly calibrated, though, it will give you a very precise number that isn’t accurate.
It is kind of weird that real world measurements always have error to them so you only really know something to a few digits of precision… but mathematical constants like pi can have effectively have unlimited significant figures (but it’s kind of pointless to have more because any real world applications only need a rather small amount of them). I feel kind of similarly about integration. It’s nice to find a closed form solution for an integral, which can make certain calculations a lot faster and more accurate… but in reality if you’re just solving an integral or two for an engineering project you’re probably better off just computing it numerically to the correct number of sig figs. There’s something a little sad about that to me.