Complete the following series. It.s very logical:

1, 4, 5, 6, 7, 9, 11, __?

If 21x = 79x, what is the value of x?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

Find the next number in the series

12, 20, 40, 72, 116, 172 ?

You are a prisoner sentenced to death. The Emperor offers you a chance to live by playing a simple game. He gives you 50 black marbles, 50 white marbles, and 2 empty bowls. He then says, 'Divide these 100 marbles into these 2 bowls. You can divide them any way you like as long as you use all the marbles. Then I will blindfold you and mix the bowls around. You then can choose one bowl and remove ONE marble. If the marble is WHITE you will live, but if the marble is BLACK... you will die.'

How do you divide the marbles up so that you have the greatest probability of choosing a WHITE marble?

How many letters are in the alphabet?

What has a bottom at the top?

Can you move 2 matchsticks to form four equal sized squares.

John is a strange liar.

He lies on six days of the week, but on the seventh day, he always tells the truth.

He made the following statements on three successive days:

Day 1: "I lie on Monday and Tuesday."
Day 2: "Today, it"s Thursday, Saturday, or Sunday."
Day 3: "I lie on Wednesday and Friday."

On which day does John tell the truth?

What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?