请问这个改怎么写代码？
求5+55+555.....+5555555555的结果
如何实现呢？望高手指导

[解决办法]
#include <iostream>

int main(void)
{
const int X = 5;
const int LENGTH = 10;
long long item = X;
long long sum = 0;
for (int i=0; i <LENGTH; ++i)
{
sum += item;
item = item*10 + X;
}
std::cout < < "5+55+555.....+5555555555 = " < < sum < < std::endl;
system( "pause ");
return 0;
}