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);
