https://www.acmicpc.net/problem/2588
using System;
namespace baekjoon
{
class Program
{
static void Main(string[] args)
{
string strFirstNum = Console.ReadLine();
string strSecondNum = Console.ReadLine();
int nFirstNum = int.Parse(strFirstNum);
int nSum = 0;
for (int i = 2; i >= 0; i--)
{
char chSecondNum = strSecondNum[i];
int nSecondNum = int.Parse(chSecondNum.ToString());
int nResult = nFirstNum * nSecondNum;
Console.WriteLine(nResult);
nSum = nSum + (nResult * (int)Math.Pow(10, 2 - i));
}
Console.WriteLine(nSum);
}
}
}