package liu0912;
public class Jiecheng2 {
public static void main(String[] args) {
double sum=0;double i=1;double j=1;
for(i=1;i<=20;i++)
{
double sum=0;
for(j=1;j<=i;j++)
{
sum2=sum2*j;
}
sum=sum+(1/sum2);
}
System.out.println("20的階乘是："+sum);
}
}