I travel all around the world but always stay in the corner. What am I?

Baseball bat and ball cost $100. If the bat cost $99 more than the ball, what is the cost of each?

A research team went to a village somewhere between the jungles of Africa. Luckily for them, they reached the day when quite an interesting custom was to be performed. The custom was performed once a year as they confirmed and was performed in order to collect the taxes from every male of the region.

The taxes were to be paid in the form of grains. Everyone must pay pounds of grain equaling his respective age. This means a 20-year-old will have to pay 20 pounds of grain and a 30-year-old will pay 30 pounds of grain and so on.

The chief who collects the tax has 7 weights and a large 2-pan scale to weigh. But there is another custom that the chief can weigh only three of the seven weights.

Can you find out the weights of the seven weights? Also, what is the maximum age of the man that can be weighed for the payment of taxes?

John is looking at Jenifer, but Jenifer is looking at Jacob. John is married, but Jacob is not.

Is a married person looking at an unmarried person ?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

You have 1023 apples and 10 bags. You have to distribute these apples in these 10 bags in any way you choose. But when I ask for a certain number of apples you have to give them in terms of bags without transferring the apples from other bags. How do you distribute the apples?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

Take away the whole and some still remain. What is it?