Why is math.pi slightly wrong?

[Dutton, Sam]

I've noticed that the value of math.pi -- just entering it at the interactive prompt -- is returned as 3.1415926535897931, whereas (as every pi-obsessive knows) the value is 3.1415926535897932... (Note the 2 at the end.)
 
Is this a precision issue, or from the underlying C, or something else? How is math.pi calculated?
 
I searched for this on the web and in this group and couldn't find anything -- but humble apologies if this has been asked before/elsewhere.
 
Sam Dutton
 





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