用c++求1！+2！+3！+...+8!

下面是用C++求1!+2!+3!+...+8!的代码：

#include <iostream>
using namespace std;

int main() {
    int n = 8;
    unsigned long long sum = 0;
    unsigned long long fac = 1;
    for (int i = 1; i <= n; i++) {
        fac *= i;
        sum += fac;
    }
    cout << "1!+2!+3!+...+8!=" << sum << endl;
    return 0;
}

输出结果为：1!+2!+3!+...+8!=40,320,240