for loop help with this problem?

result i should be getting is 1086420 but im getting '101112' anyone see any mistakes?

 

using System;


namespace HelloWorld
{
class Program
{


static void Main(string[] args)
{
string result = "";

for (int i = 10; i < 13; i++)
{
result += i;
}
Console.WriteLine(result);
Console.ReadLine();
}

}
}