const int cnNumberOfQuestions = 10;
string response = string.Empty;
Console.WriteLine("MathSpeeder - Firing neurons and nimbling fingers");
Console.WriteLine("There are {0} math questions", cnNumberOfQuestions);
Console.Write("Ready to play (y/n)? ");
response = Console.ReadLine().ToLower();
Console.WriteLine();
if (response.Equals("y"))
{
    int operand1, operand2, result, answer;
    int score;
    Random rand = new Random();
    score = 0;
    DateTime start, end;
    start = DateTime.Now;
    int i;
    for (i = 0; i < cnNumberOfQuestions; ++i)
    {
        operand1 = rand.Next(1000);
        operand2 = rand.Next(1000);
        result = operand1 + operand2;
        response = string.Format("Q{0}", i + 1).PadLeft(3);
        Console.Write("{0}: {1} + {2} = ", response, operand1, operand2);
        response = Console.ReadLine().Trim();

        try
        {
            answer = Convert.ToInt32(response);
            if (answer == result)
            {
                ++score;
                Console.WriteLine("     Correct!\n");
            }
            else
            {
                Console.WriteLine("     Wrong!\n");
            }
        }
        catch
        {
            Console.WriteLine("     Wrong!\n");
        }
    }
    end = DateTime.Now;
    TimeSpan ts = end - start;
    Console.WriteLine("You got {0} correct answers out of {1} questions", score, cnNumberOfQuestions);
    Console.WriteLine("Total time taken: {0,0:f2} seconds", ts.TotalSeconds);
    Console.WriteLine("Average time per question: {0,0:f2} seconds", ts.TotalSeconds / (double)cnNumberOfQuestions);
}
else
{
    Console.WriteLine("Challenge the MathSpeeder next time then!");
}

Console.WriteLine();
Console.WriteLine("End of program");
Console.ReadLine();