Chapter 1: seek common? Decimal and S (D, n)

int main()
{
    
	int d, j, n;
	double t, s;
	printf("  please enter an integer d, n:");
	scanf("%d, %d", &d, &n);
	t = s = 0;
	for (j = 1; j < n; j++)
	{
    

		t = t / 10 + (double)d / 10;
		s += t;
	}
	printf(" S(%d, %d) = %.8f\n", d, n, s);
	return 0;
}

The results verify that ：