使用while语句计算1+1/2!+...+1/20!的和

计算1+1/2!+...+1/20!的和。

double n = 1.0d;
double result = 0.0d;
while(n <= 20) {
    double m = 1.0d;
    double mult = 1.0d;
    while (m <= n) {
        mult *= m;
        m++;
    }
    n++;
    result += 1 / mult;  
}
System.out.println(result + 1);