问题及解答

找到 $N$, 使得 $\sum _{n=1}^N{\displaystyle \frac{1}{n}}<2\pi$, 但 $\sum _{n=1}^{N+1}{\displaystyle \frac{1}{n}}>2\pi$.

Answer:  $N=300$.

{
fun f(){
  var N=0;
  var sum=0;
  var pi=3.141592653589793238462643383279;
  pi=2*pi;
  while(sum<pi) {
    N=N+1;
    sum=sum+1/N;
  }
  print "N=",N-1;
  }
}