//计算sn = a+aa+aaa;
int test(int a,int n)
{
    
    
	int sn = 0,i,ever = a;
	for(i = 1;i <= n;i++)
	{
    
    
		sn += a ;
		a = a * 10 + ever;
	}
	
	return sn;

}

//利用while 计算
double test1()
{
    
    
	double result = 0;
	int m,n = 1;
	while(n <= 100)
	{
    
    
		m = n + 1;
		result += (1.0/n - 1.0/m);
		n += 2; 
	}

	return result;
}