You need to check that your friend, Bob, has your correct phone number, but you cannot ask him directly. You must write the question on a card and give it to Eve who will take the card to Bob and return the answer to you.

What must you write on the card, to ensure Bob can encode the message so that Eve cannot read your phone number?

The court takes decision to relax the sentence given to criminal if he can solve a puzzle. Criminal has to take decision to open one of the doors.

Behind each door is either a lady or a tiger. They may be both tigers, both ladies or one of each.

If the criminal opens a door to find a lady he will marry her and if he opens a door to find a tiger he will be eaten alive. Of course, the criminal would prefer to be married than eaten alive.

Each of the doors has a statement written on it.

The statement on door one says, “In this room there is a lady, and in the other room there is a tiger.”

The statement on door two says,”In one of these rooms there is a lady, and in one of these rooms there is a tiger.”

The criminal is informed that one of the statements is true and one is false. Which door should the criminal open?

You need to boil eggs for exactly 9 minutes.

But you have only 2 hourglasses – one measures 4 minutes and the other measures 7 minutes. How do you measure exactly 9 minutes without the process taking longer than 9 minutes?.