Logical Conjunction and Disjunction

private void Exercise_Load(object sender, EventArgs e)
{
   var numbers = new List<int>();

   numbers.Add(12);
   numbers.Add(45);
   numbers.Add(38);
   numbers.Add(5);
   numbers.Add(128);
   numbers.Add(525);
   numbers.Add(2448);
   numbers.Add(39);
   numbers.Add(632);
   numbers.Add(207);

    var number = from n
                 in numbers
                 where n % 2 == 0 && n <= 100
                 select n;

    foreach (var member in number)
        lbxNumbers.Items.Add(member.ToString());
}

This would produce:

Once again, remember that the use of parentheses makes it easier to read the code and better understand it:

private void Exercise_Load(object sender, EventArgs e)
{
    var numbers = new List<int>();

   numbers.Add(12);
   numbers.Add(45);
   numbers.Add(38);
   numbers.Add(5);
   numbers.Add(128);
   numbers.Add(525);
   numbers.Add(2448);
   numbers.Add(39);
   numbers.Add(632);
   numbers.Add(207);

    var number = from n
                 in numbers
                 where (n % 2 == 0) && (n <= 100)
                 select n;

    foreach (var member in number)
        lbxNumbers.Items.Add(member.ToString());
}

Or better yet:

private void Exercise_Load(object sender, EventArgs e)
{
    var numbers = new List<int>();

   numbers.Add(12);
   numbers.Add(45);
   numbers.Add(38);
   numbers.Add(5);
   numbers.Add(128);
   numbers.Add(525);
   numbers.Add(2448);
   numbers.Add(39);
   numbers.Add(632);
   numbers.Add(207);

    var number = from n
                 in numbers
                 where ((n % 2) == 0) && (n <= 100)
                 select n;

    foreach (var member in number)
        lbxNumbers.Items.Add(member.ToString());
}

To negate a conjunction, precede it with a ! operator. Remember that a conjunction is made of two parts. Therefore, if you want to negate only the first part, precede it with !. If you want to negate the whole conjunction, put the conjunction in parentheses but precede it with ! (outside the parentheses).

When creating a LINQ statement, you can use a logical disjunction. You do this with the C#'s OR operator, which is ||.