C语言：前n项和（Sn=a+aa+aaa+aaaa）

#include<stdio.h>计算数字a的前n项和 Sn=a+aa+aaa+aaaa+aaaaa
int main()
{
	int a = 0;
	int n = 0;
	scanf("%d %d", &a, &n);
	int sum = 0;
	int i = 0;
	//int t = a;
	int ret = 0;
	for (i = 0; i < n; i++)
	{
		//sum = sum + a;法1
		//a = a * 10 + t;
		ret = ret * 10 + a;
		sum += ret;
 	}
	printf("%d\n", sum);
	return 0;
}