Can you find out the next digit in the following series ?

0, 0, 1, 3, 2, 6, 3, 9, 4, 12, 5, ?

13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

Can you place six X (crosses) in below board without making three in a row in any way ?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

What has hands, but can’t clap?

John speaks the truth only once a day in a week. Below are a few hints for you:

First: Days are Sunday, Monday and so on.
Second: One day he says, "I lie on Monday and Tuesday".
Third: On the next day, he says, "Today is either Thursday, Saturday or Sunday".
Fourth: On the next day, he says, "I lie on Wednesday and Friday".

Can you identify the day on which he speaks the truth?

A farmer and his neighbour once went to Emperor Akbar"s court with a complaint. "Your Majesty, I bought a well from him," said the farmer pointing to his neighbour, "and now he wants me to pay for the water."
"That"s right, your Majesty," said the neighbour. "I sold him the well but not the water!"?
The Emperor asked Birbal to settle the dispute. How did Birbal solve the dispute?

If in a car race, the man who came two places in front of the last man finished one ahead of the man who came fifth, how many contestants were there?

They are the five precious gems of an everyday sort and all can be found on a Tennis Court. Who are they?

I am lying and I always lie. Tell me whether I am lying or telling the truth.