When you enter a number different than 2 you actually read another line which you do not process:
if (answer != 2)
{
Console.WriteLine("Wrong answer. Press enter to get your next sum");
Console.ReadLine();
}
Your confusion could be because of this line. Change it to:
if (answer != 2)
{
Console.WriteLine("Wrong answer. Press enter to get your next sum");
}
else{
Console.WriteLine("Correct answer");
break;
}
solved How to break out of a while loop in C#. Break not working [closed]