c++入门题。求sn=a+aa+aaa+…+n个a。大神们看看我的程序哪里有问题

Question

Answer 1

 图片分辨率太低，看不清。
写一个给你
int a = 2;
int n = 5;

int b = a;
int sum = 0;
for (int i = 1; i < 5; i++)
{
sum += b;
b *= 10;
b += a;
}
cout << sum;