If eleven plus two equals one, what does nine plus five equal?

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

Jigsaw captured 100 people and make them stand in a circle and all these people are labelled as Person1, Person2, Person3... Person100. He made them play a crazy game in which Person 1 shot Person 2 and pass the gun to the next person and so on until one stands alive.

Which person will survive in the end?

When we see 2 but call 10?

Considering the below equation:

V + II - VI = 10
IV - X + VIII = 20
IV - VII + VI = 30

Then, I + II + III = ?

I have no life, but I can die. What am I?

Count the number of triangles in the picture below:

In the image below, you can see two glasses and two matchsticks.You need to move four matchsticks in such a manner that the crosses come inside the glasses. Note: you cannot move the crossed.

If it took eight men ten hours to build a wall, how long would it take four men to build it?

What is more useful when it is broken?