So we have to call "pi" what was previously named by the greek letter.
Anyway, to a mathematician 4 digits - as 1415 - for pi are no more satisfying than 1.000.000, since pi is not rational - there is no possibility of writing it in a decimal form repeating again and again the same string of digits ,
as, for example , in
7,1232412341234...
Ciao
Emanuela