Question

1+2!+3!+4!..............n!

Answer 1

#include <iostream>
using namespace std;
// we're going to calculate factorial from number
int main(){
cout<<"Enter n\n";
// we ask people for N
int n ;cin>>n;
// 1*2*... n
long long num=1;
//for 1!+2!+3!+...+N!
long long sum = 0;
// we multiply 1 * 2 * 3 ... N
for (int i = 1 ; i <= n ; i++){
num *= i;
sum += num;
}
// out the answer
cout<<"the answer is: "<<sum<<endl;

return 0;
}