Chapter 1: extend the same code decimal sum s (D, n)

int main()
{
    
    int a, b, d, j, n;
    double t, s;
    printf("  please enter an integer d, n; ");
    scanf("%d, %d", &d, &n);
    a = d;
    b = 1;
    while (a > 0)
    {
    
        b = b * 10;
        a = a / 10;
    }
    t = s = 0;
    for (j = 1; j <= n; j++)
    {
    
        t = t / b + (double)d / b;
        s += t;

    }
    printf(" s(%d, %d) = %.8f\n", d, n, s);
    return 0;
	
}

result ：