用C++编程求Sn，n个a

Question

Answer 1

#include<iostream>
#include<cmath>
using namespace std;
int main() {
    int n,a,t=0,s=0;
    cout<<"输入a:";
    cin>>a;
    cout<<"输入n:";
    cin>>n;
    for(int i=0;i<n;i++){
        t=t*10+a;
        s+=t;
    }
    cout<<s;
    return 0;
}