How to printf long long

Question

I\'m doing a program that aproximate PI and i\'m trying to use long long, but it isn\'t working. Here is the code

#include
#include

        

Answer 1

    // acos(0.0) will return value of pi/2, inverse of cos(0) is pi/2 
    double pi = 2 * acos(0.0);
    int n; // upto 6 digit
    scanf("%d",&n); //precision with which you want the value of pi
    printf("%.*lf\n",n,pi); // * will get replaced by n which is the required precision