static void conversion(string value)
{
    Console.WriteLine("{0} to decimal is {1}.",
        value, Convert.ToInt32(value, 16));
    Console.WriteLine("{0} to decimal is {1}.\n", value,
        Convert.ToString(Convert.ToInt32(value, 16), 2));
}

static void Main(string[] args)
{
    conversion("2A3E");
    conversion("FA");
    conversion("FFFF");
    conversion("5A0E9");
}