Can you convert the number zero(0) into a positive number using just one mathematical operator ?

The captain of a ship was telling this interesting story: "We travelled the sea far and wide. At one time, two of my sailors were standing on opposite sides of the ship. One was looking west and the other one east. And at the same time, they could see each other clearly." How can that be possible?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

How many Watermelons are there in the below picture?

Which part of London exists in France as well ?

I look at you, you look at me, I raise my right, you raise your left. What am I?

Three men in a cafe order a meal the total cost of which is $15. They each contribute $5. The waiter takes the money to the chef who recognises the three as friends and asks the waiter to return $5 to the men.

The waiter is not only poor at mathematics but dishonest and instead of going to the trouble of splitting the $5 between the three he simply gives them $1 each and pockets the remaining $2 for himself.

Now, each of the men effectively paid $4, the total paid is therefore $12. Add the $2 in the waiters pocket and this comes to $14. Where has the other $1 gone from the original $15?

Our product and our sum always give the same answer. Who are we?

How many triangles can you count in the figure given?

Replace the question mark with the correct number.